SEPARATION OF POWER AND LEGISLATIVE INSTITUTIONS: THE CONSTITUTIONAL THEORY OF LEGISLATIVE ORGANIZATION If a tree falls on the President, do members of the House get hurt? Chapter 3 A Test of the Constitutional Theory of Legislative Organization Gisela Sin University of Michigan I claim that movements in the preferences of the Senate and president that change the identity of the “representative bill”1 that will be approved by either a coalition of a House majority, Senate majority and the president or a House and Senate supermajority, can induce House members to alter the balance of power in the House. In this chapter I examine that result by analyzing institutional changes adopted by the U.S. House from 1879 until 2001. Utilizing an extensive data set and simple statistical models, I show that when House members face a new bargaining situation caused by changes in the Senate and/or the president, they are far more likely to modify their organizational arrangements. Throughout congressional history, changes in the preferences of the president and/or the composition of the Senate have regularly been followed by significant alterations in the distribution of power in the House—even during times of stability within the House itself. These alterations occur in ways that the Constitutional Theory of Legislative Organization (CTLO) predicts, but past scholarship does not. In the first section of this chapter I delineate the predictions developed from the Constitutional Theory and from Traditional Theories,2 emphasizing their differences, especially in situations in which the membership of the House remains constant across terms. While Traditional Theories predict no influence of ideological changes in the Senate and the president on decisions regarding the internal distribution of power in the House, CTLO predicts that preferences of the Senate and the President have a large impact on the balance of power in the House. Even when we hold constant the preferences of members of the House on substantial issues, the House may still undergo institutional change. More 1 A representative bill embodies the joint expectation of all the members of the House concerning the issues that will be decided on the next legislative term and aggregates the set of initial bargaining positions that the House presents to the Senate in negotiations over the ensuing legislative term. 2 By Traditional Theories, I mean previous scholarly work that has focused on the internal organization of the House and have claimed how well the internal dynamics of the House serve different objectives: (1) make gains from exchange possible (Shepsle 1979, Shepsle &Weingast 1981, 1987, 1995; Weingast & Marshall 1988), (2) advance the interests of the median member of the House (Krehbiel and Gilligan 1989,1990; Krehbiel 1991) or (3) ensure the advantages of the majority party (Cox and McCubbins 1994, 2005; Rohde 1991; Aldrich and Rohde 1997, 1998, 2000, 2001). Although different in their specific arguments, they all claim that institutional design is a consequence of House members’ preferences. For a more detailed explanation of their arguments and results, see previous chapter. 1 specifically, CTLO predicts that even when House members’ preferences over substantive issues do not change, changes in the partisan balance of the Senate and/or the identity of the president that affect the set of achievable legislative outcomes induce important changes in the in the preferences of House members over the distribution of power in the House. Extant theories consider that the preferences of exogenous institutions are irrelevant when House members make decisions regarding the organization of the House. In the second section I present the data, formulate the concepts and develop indicators of changes in the distribution of power in the House and of the variables that help me understand these changes: constant Houses across congressional terms and modifications in the partisan balance of the Senate and the identity of the president. In the third section, I analyze the data using exact tests where the repeated sampling assumptions of standard techniques like 2 tests are difficult to believe. I specifically test the claim that changes in the Senate and/or president have no effect on the decision to alter rules and procedures of the House. The results allow me to reject such claim. Furthermore, the combination of results shown in this chapter provides strong support for the argument that changes in the majority of the Senate and/or identity of the president significantly affect decisions to alter the distribution of power in the House. After presenting the main results, I check for the existence of overt and hidden bias resulting from a missing, yet theoretically relevant, variable. Bias is present when there are systematic differences between congresses that experience or do not experience changes in the Senate and/or president. To control for overt bias, I include variables that the existing literature suggests are correlated with the institutional outcomes. The results show that the effect of changes in the Senate and /or the president remain strong even when depedent upon alternative explanations. To address hidden bias, I conduct a sensitivity analysis to determine how large the effect of unobserved variables would need to be in order to qualitatively alter the results. The analysis shows that attributing responsibility for institutional change to an unobserved covariate 2 rather than to an effect of changes in the Senate and/or the president would require a covariate four times as powerful as changes in those exogenous actors. I also assess whether my results are robust across a variety of definitions of congressional stability. The results show that my conclusions are robust to different measurements of this variable. In the last section, I conclude by drawing some implications of my result. 1. Hypothesis and Predictions Traditional Theories of legislative organization assume that House members do not take the president and the Senate into account when organizing internally. They claim that when rational and strategic legislators decide on internal organizational matters, they only take into account internal House politics. Therefore, institutional design is a consequence of House members’ preferences. Two observable implication of this claim are that we should observe changes in the rules of the House only when its membership changes significantly and not when its membership remains constant, and that those changes in rules and procedures should not be associated with changes in the preferences of the Senate and/or president. An alternative point of view, offered by the Constitutional Theory, addresses the following question: assuming that House members do take into account the president and the Senate when organizing internally, what observable consequences should follow? This perspective claims that when changes in the partisan balance of the Senate and/or the identity of the president modify the characteristics of the ‘representative’ bill that can be approved by a coalition among the Senate, House and the president or a supermajority from the House and Senate, we can expect modifications in the internal distribution of power in the House. The following table compares the predictions of both theories in more detail. 3 TABLE 1. Predictions of Traditional Theories of Legislative Organization and the Constitutional Theory of Legislative Organization in Senate and /or president.3 ~ in House in rules/ procedures of the House ~ in Senate and/or president ~ in House in Senate and /or president.3 in House ~ in Senate and/or president in House CTLO: YES CTLO: NO CTLO: YES CTLO: YES Traditional Theories: NO Traditional Theories: NO Traditional Theories: YES Traditional Theories: YES The table represents all possible combinations of existence or absence of changes in the membership of the House, the partisan balance of the Senate and the identity of the president.4 The cells show the predictions of the Constitutional Theory and the Traditional Theories with respect to whether changes in the rules and procedures of the House should be observed. First, consider the cases where the preferences of members of the House change (last two columns). In these cases the CTLO and Traditional Theories are observationally equivalent. Both theories, in both cases, predict changes in rules and procedures. For Traditional Theories, changes in the membership of the House are a sufficient condition for producing an internal redistribution of power. For CTLO, changes in the preferences of members of the House, Senate and president that change the “representative bill” that can be approved by a coalition among the Senate, House and the president or a supermajority from the House and Senate, induce House members to alter the distribution of power in the House. These changes in the Senate and/or the president need to alter the identity of the ‘representative’ bill that can be approved by a coalition among the Senate, House and the president or a supermajority from the House and Senate. 3 4 A more precise and specific definition of these concepts is developed in the next section. 4 Second, consider those cases where the identity of the majority party in the House and the relative size of its factions are held constant (first two columns). Traditional Theories and the Constitutional Theory disagree in their predictions. Traditional Theories predict there will be no observable changes in the organization of the House, regardless of changes in the president and/or the Senate. According to these theories, if neither the median of the floor nor the party composition changes dramatically, a redistribution of power should not occur. More specifically, Traditional Theories forecast no differences between the first two columns. Even if we consider that some changes in rules and procedures of the House could occur due to factors other than changes in the preferences of House, Senate or president, Traditional Theories would predict that the distribution of those cases across the first two columns should be equal. As a result, Traditional Theories have very distinct and clear predictions with respect to the probabilities of changes in rules and procedures of the House when the preferences of House members do not experience changes: such changes should either not occur, or if they do occur, they should be independent of changes in the Senate and/or Presidency. In contrast, the Constitutional Theory predicts that holding constant the identity of the majority party in the House and the relative size of its factions, modifications in the partisan balance of the Senate and/or the identity of the president should produce, under certain conditions, observable changes in the rules and procedures of the House. That is, when changes in the president and/or Senate alter the set of bills that would be accepted by either a majority of the House, Senate and president or a supermajority in the House and Senate, then House legislators have an incentive to incorporate those changes into their decisions regarding distribution of power.5 If the Constitutional Theory is correct, we should observe that most of the Houses where preferences are held constant across two consecutive congressional terms and that have modified their internal distribution of power should have experienced a change in the partisan balance of the Senate and/or the identity of the president. The Constitutional Theory 5 For a formal statement of the predictions, see Sin and Lupia 2005. 5 would predict clear differences between the first two columns. We should discern a noticeable pattern, where constant Houses that changed their rules and procedures are situated predominantly in the first column. In what follows I focus on the distinct observable implications produced by Traditional Theories and the CTLO. Both theories predict new power arrangements when House membership changes, however only the Constitutional Theory predicts a change in the distribution of power in the House when the preferences of House members remain constant from one congressional period to the next. These pivotal events provide a litmus test for both the CTLO and Traditional Theories, allowing one or both to be refuted. If CTLO is right, then the new insights regarding the timing and causes of legislative organization can change our understanding of why the House decides to distribute power among its members as it does. Furthermore, CTLO would explain a whole range of institutional changes that existing theories of legislative organization do not. More generally, if we find that the proportion of Houses that initiate changes is far greater after a change in the Senate and/or president than when such changes do not occur, then CTLO could provide evidence for an endogenous theory of institutional choice. To test whether or not changes in the Senate and/or president influence House members’ decisions regarding distribution of power in the House, I examine major rule changes in House procedures over several decades. More specifically, I study all Congresses from 1879 until 2001 in which the composition of the House remained constant across two consecutive terms. I compare situations where the House, Senate and president remained constant to situations were either the Senate or the president or both changed. These comparisons allow me to establish whether the partisan composition of the Senate and the identity of the president cause changes in the power sharing arrangements of the House. In what follows I present the data, describe the nature of the empirical study, test my hypothesis and explain the implications of my findings. I 6 also test for overt and hidden bias. In the last section I assess the robustness of the results to different operationalization of the variables. 2. Data Dependent Variable: Changes in the distribution of power in the House. Changes in the distribution of power in the House refer to changes in the organization of the House that entail a modification in the balance of power among its members. For example, decisions that affect committee staffing and funding in turn affect what committee chairs and members can do; organizational decisions that reshape committee boundaries entail a redistribution of power from one committee to another. A rule change in House procedures means that the power different House members had prior to the change no longer exists. The changes in rules produce a new configuration of the power in the House. To operationalize this concept, I use Cox and McCubbins’ (2005) list of rules and organizational changes in the House from the 46th Congress until the 100th Congress.6 First, Cox and McCubbins combed through “standard online databases [they used Voteview 2.9] for all recorded votes pertinent to rule and organizational changes” (2005:109). That is, they counted “each resolution (or amendment to a resolution) that changed House rules or organization and got one or more roll call votes.”(2005:110). This method for counting changes could have missed any instances where the Speaker makes a ruling that changes the rules of the House but that is never challenged in a roll call vote. Similarly, we miss instances where rules change as a result of a proposal that is adopted without a roll call vote at any stage of its consideration. Despite these potential omissions, we are satisfied that our method captured all of the major rules changes in the House over the time period we investigate; neither Schickler nor Binder, nor any of the other standard secondary sources, report any rule changes that we miss. (Cox and McCubbins 2005:153) Second, after building the full list they excluded some resolutions that were in effect for less than six months as well as other that had no discernible partisan consequences. In particular, they 6 For the 101st-106th Congress I followed their same procedures. 7 “considered rule changed resolutions as having partisan consequences if at least one of the roll call votes on the resolution was a party vote (pitting over 50% of Democrats against 50% of Republicans)” (2005:154)7. Cox and McCubbins’ method yielded a larger number of rule changes than the methods of both Binder (1997)8 and Schickler (2001)9. However, a few of the changes included by those two scholars would have failed one of Cox and McCubbins’ two selection criteria (partisan effect or short duration). For completeness, however, they included all rules cited by Binder or Schickler in the data set. (Cox and McCubbins 2005:111 footnote 64). Cox and McCubbins’ final list is composed of “124 resolutions with rule or organizational changes in the period 1880-1988 that had non-trivial partisan effects” (2005:111)10. Explanatory Variables Changes in the Senate. We know there exists a change in the Senate when the: - Majority party in the Senate changes. - Majority party in the Senate gains or losses the ability to invoke cloture11. 7 Thanks to the generosity of Gary Cox, I was able to examine those excluded rules and procedures. None of those rules changes affect my results. 8 Binder’s (1997) selection criterion for changes in rules that affect minority rights is the following: “Under the identification standard, any rule identified by the minority party as a minority right is counted as such…Under the effect standard, a rule qualifies as a minority right if over time its effects redound to the advantage of the minority party –allowing it to challenge or influence majority control of the agenda…These two criteria offer a set of decision rules for evaluating whether or not a rule counts as a minority right” (Binder, 1997:23-24). 9 Shickler’s selection criterion for organizational changes is the following: “I define an “important” institutional change as one that historians or congressional specialists perceive to have had substantial effects on congressional operations. I operationalize this definition by counting a change as important if five sources each suggest that the institutional change in question had such effect” (Schickler, 2001:277). 10 For more information on their method, selection criteria as well as for a list of changes, see Cox and McCubbins (2005) Chapter 4 and its appendix. 11 The number of Senators required to invoke the cloture rule has varied through history: “Since 1975, three-fifths of the membership has been required to invoke cloture…With some variations, two-thirds majorities were required from 1917 to 1975. Before 1917 the Senate had no formal rule for ending debate and moving the previous question.” (Wawro and Schickler, 2003:1). 8 Why should this latter condition be considered a change that modifies the partisan balance of the Senate? “Even though the Constitution implies that only a majority of the US Senate is required to pass legislation, the rules of the modern Senate concerning debate effectively mean that supermajorities are necessary for passage” (Wawro and Schickler, 2003:1). In another paper, Wawro and Schickler claim that cloture reform could have been meaningful in the sense that it reduced the uncertainty that legislative entrepreneurs faced when trying to push legislation and how it might have increased the efficiency of passing legislation in the Senate by providing a clear threshold for cutting off debate and bringing legislation to a final vote…[T]he adoption of the cloture rule had a substantive impact on the operation of the Senate, contrary to what the conventional wisdom would have us believe. (Schickler and Wawro, 2004:32) Therefore, whether a party has enough votes to invoke cloture affects its bargaining position with respect to the minority party, the House and the president. Thus I consider the Senate’s partisan balance altered when a party reaches or loses the filibuster pivot point. Changes in the president: There exists a change in the president when a new president inaugurates a term. Changes in the House Changes in the House refer to alterations in the membership of the House. That is, whenever the median member of the floor, the median member of the party or the level of intraparty homogeneity and inter-party heterogeneity changes considerably, a change in the House has occurred. The operationalization of this variable involves two indicators: - First, the replacement of the majority party by another party. - Second, a change in the relative size of the factions of the majority party. 9 This means I consider the House to be constant when the identity of the majority party across consecutive congressional terms is the same and the relative sizes of the factions within the majority party are equivalent.12 In order to identify majority party factions and their relative sizes for each Congress, I rely on secondary sources whose focus is party factions in presidential primaries and in Congress. In general, these studies place legislators into factions based on their party ideology, the region they come from and their home state. Or this latter point, scholars agree that party ideology has been unified at the state and local levels, which means that a state’s party delegation to Congress is considered ideologically cohesive. Scholars classify party factions in the House of Representatives in the following way: Democrats: o 1900-1930: split between supporters of William Jennings Bryan in the rural west and south, and anti-Bryan in the urban east (legislators coming from CT, DE, ME, NH, NJ, NY, PA, MA, RI AND VT (Wiseman 1988, Kent 1928); o 1930 to present: division between southern conservatives (Kentucky, Oklahoma and the eleven states that seceded from the Union) and northern liberals (remainder of the states) (Reiter 2001 and 2004, Aldrich 1995, Schousen 1994, Rohde 1991, Smith and Deering 1984, Sinclair 1982, Brady and Bullock 1980, Shelley 1977, Stang 1974, Manley 1973, Rohde and Shepsle 1973, Moore 1967, Patterson 1966, and Burns 1963). 12 My objective was to find a good measure of changes in the House across two consecutive congressional terms that did not depend on roll call voting and legislator’s ideal points, essentially because such measures are endogenous to my dependent variable. Votes on the floor are the product of the agenda set by legislators who are given power by rules and procedures. For example, more heterogeneous voting from one Congress to the next could be just indicating that, as a result of changes in rules and procedures, more controversial issues could make it to the agenda. As a result, I tried to avoid a measure that was endogenously determined by my dependent variable, changes in the organization of the House. Later in the paper, I conduct robustness tests on my results using changes in DW-NOMINATE scores between two successive congresses as the indicators of changes in House membership. The results show that the findings are robust to changes in this measurement. 10 Republicans: o 1898-1929: split between Progressives in the West (all states west of the Mississippi river plus Wisconsin and Minnesota) and Conservatives in the East (all the states east of the Mississippi river except Wisconsin and Minnesota) (Schousen 1994, Aldrich 1989, Shepsle 1978, Galloway 1976, Barfield 1970, Mayer 1967, Wilensky 1965, Hofstadter 1963, Berdahl 1951, Gwinn 1957, Nye 1951, Chiu 1928, Hasbrouck 1927). Scholars also agree in that the Depression marked the end of the Progressives as members either lost their seats to New Deal Democrats or joined the Democratic Party. o Since 1940: division between liberals/moderates in the east (CT, DE, ME, MA, NH, NJ, NY, PA, RI, AND VT) and conservatives from the Midwest, West and South (Aldrich 1995, Schousen 1994, Rohde 1991, Rae 1989, Reinhard 1983, Sinclair 1982, Reichard 1975, Burns 1963). After collecting and classifying the data on changes in rules and procedures, changes in the president and Senate, and constant Houses from 1879 until 2001, I built a data set composed of the procedural and organizational changes in the House from the 47th Congress until the 106th Congress. As explained above, most of the data used has been previously compiled by leading scholars in the field and is widely accepted as highly accurate. The dependent variable, i.e. changes in the rules and procedures of the House, is binary, where 1 indicates a change in rules and procedures and 0 represents no change. I also coded changes in the explanatory variables (House, Senate and president) as defined above. These are also binary variables, with 1 indicating the existence of changes and 0 indicating the absence of variation. In order to specifically test CTLO’s hypothesis against the null I selected Congresses where the identity of the majority party remained constant across Congresses and the relative size of party factions 11 within the majority party was equivalent.13 Out of the total population of 61 Congresses from 1879 until 2001, 41 Congresses met the criteria.14 3. Methods and Results As mentioned above, hypotheses derived from Traditional Theories and the Constitutional Theory of Legislative Organization markedly differ with respect to the timing of decisions regarding redistributions of power in Houses where members’ preferences across consecutive terms did not change. Traditional Theories have very firm predictions with respect to the 41 Houses in my study. Consider Table 2 below, in which I separate the Congresses based on two criteria: whether or not changes in the Senate or president occurred, and whether or not the House adopted new rules. TABLE 2. in Rules in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House ~ in Rules Constitutional Theory predicts more changes here All theories predict no differences Traditional Theories make very specific predictions about what the values of this table should be: 1. A substantial majority of Houses should not experience changes in rules and procedures. Most Houses should fit the second column of Table 2. For Traditional Theories, changes in the distribution of power in the House are a consequence of changes in the preferences of House members. Therefore, if these preferences remain constant, as it is the case in 13 As mentioned before, it is precisely with respect to these constant Houses that Traditional Theories and CTLO have very distinct predictions. 14 If we relax one of these conditions and only take into account those Congresses in which the majority party from one period to the next is the same, then the total number of Congresses is 48. Later on I check the robustness of my results to this measure. 12 the 41 Houses analyzed, there is no reason to expect a change in the power sharing agreement. 2. A baseline number of Houses could change their rules and procedures even when their membership remains constant. In some special circumstances, factors other than changes in House members’ preferences may be important in determining redistributions of power. Therefore, Traditional Theories expect that a small percentage of Houses could change their rules and procedures even when the membership does not undergo changes. 3. Among the Houses that fit the first column (i.e. decided to change their rules) there should be no differences between the number that experienced changes in the Senate and/or president and those that did not. The same is true for Houses that fit the second column (i.e. decided not to change their rules). The number of Houses that correspond to each row in each column should be approximately equal. For Traditional Theories decisions to redistribute power in the House are independent of the preferences of the Senate and the president. Therefore, decisions regarding rearrangements of the balance of power should not show any pattern depending on whether or not changes in those outside institutions occurred. Contrary to the conventional wisdom, the Constitutional Theory predicts important differences between Houses that experience changes in the Senate and/or presidency and those that do not: 1. Given a change in the Senate and/or president’s preference, a large proportion of Houses should change their rules and procedures. 2. Given no change in the Senate and/or president’s ideal point, a large proportion of the Houses should NOT change their rules and procedures. In contrast to Traditional Theories, the numbers across rows should not be identical because the decision to change the House’s rules and procedures is not independent of changes in the Senate and/or president. The Constitutional Theory predicts that the existence or absence of 13 changes in the partisan balance of the Senate and/or the identity of the president have an effect on whether legislators decide to alter an existing power sharing arrangement. Moreover, we expect the number in the top-left quadrant to be much higher than the bottom-left and the number of cases in the bottom-right quadrant to be much higher than the upper-right. The Constitutional Theory makes no predictions with respect to the total number that should fit each column. The Constitutional Theory claims that most congresses that experienced change sin the Senate and/or president should be concentrated in the upper-left and bottom-right cells. This prediction is very different from Traditional Theories, which predict no difference between rows. Table 3 shows the results. Do changes in the partisan balance of the Senate or the identity of the president have a causal effect on House’s rules and procedures? Of the 22 Houses that experienced changes in the partisan balance of the Senate and/or the identity of the president, 82% (18) changed their rules and procedures. Of the 19 Houses that did not experience a change in the Senate and/or the president, 63% (12) did not change their rules.15 What do these results mean for the null and alternative hypothesis? TABLE 3. Each cell represents the number of ‘constant’ Houses from across consecutive congressional periods that fit both categories. in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House in Rules 82% (18) ~ in Rules 18% (4) Total 100% (22) 37% (7) 63% (12) 100% (19) First, a substantial majority of Houses are concentrated in the first column. More than 60% of the 41 Houses analyzed did change their distribution of power even though their membership remained constant. Furthermore, 61% seems a much higher percentage than the baseline number of Houses that could have changed their rules and procedures due to factors other than changes in 15 An extensive contingency table with all the Congresses included in each cell is presented in the appendix. 14 preferences of House members. These results are difficult to explain with Traditional models. Traditional Theories would never have predicted that such a high proportion of Houses would change their rules and procedures when House membership is held constant. The results provide no support for existing theories of legislative organization. First, in each column the results are significantly different across the rows. If changes in the Senate and president did not have any influence on decisions whether or not to change the balance of power within the House, then the number of Houses in each row should be equal. To the contrary, around 73% of those Houses that experienced changes in rules also experienced changes in the Senate and/or president, while 75% of Houses that did not change their rules, did not experience such changes in the Senate and/or president. These high percentages seem to suggest, in line with the Constitutional Theory, that changes in outside institutions’ preferences may have an effect on decisions regarding redistributions of power within the House. In addition, 82% of those Houses that experienced changes in the preferences of the Senate and/or president changed their distribution of power. Among those that did not experience changes in the Senate and/or the president, 63% of Houses maintained a constant balance of power across congressional terms. These results show a significant pattern: Houses do concentrate on the upper left and bottom right cells. If changes in the preferences of outside institutions with which the House must coalesce were not important in House members’ calculations, then we shouldn’t see such a pattern. That a significantly higher number of units do correspond to those cells suggests that the preferences of the Senate and the president may enter into House legislators’ estimations about the future bargaining environment. Altogether, my findings show that a group of decisions that effectively change the balance of power in the House can be explained by the Constitutional Theory, but not by Traditional Theories. These results would never have been expected had we subscribed only to the argument set forth by Traditional Theories. Empirical evidence seems to indicate that House 15 legislators may condition their decision to redistribute power within the House based upon the preferences of the Senate and the president. On the surface, the data may suggest support for the Constitutional Theory. However, more formal analysis is needed to support my theory. I employ Fisher’s exact test to measure the independence of outcomes (institutional change in the House) on treatments (change in the president or Senate). In other words, the test determines whether a particular independent variable has an effect on the dependent variable.16 In the test, every unit i (units in this case correspond to each Congress) “exhibits a response that is observed some time after treatment. To say that the treatment has no effect on this response is to say that each unit would exhibit the same value of the response whether assigned to treatment or control” (Rosenbaum 2002:27). The null hypothesis in Fisher’s exact test alleges that the response (r) is constant, and that it does not vary with the treatment it receives: r1i r0i , where 1 indicates the presence of treatment and 0 its absence, and i 1,..., N . The test statistic is the number in the upper left cell: the number of responses equal to 1 in the treated group and its p-value represents the probability of a result as rare or more rare than the actual observed value if the null hypothesis were true. Under the hypothesis of no effect, the distribution of the test statistic is the hypergeometric distribution17: “the upper corner cell (of the 2x2 table) has the hypergeometric distribution, and this is the basis for Fisher’s exact test of the hypothesis of no effect” (Rosenbaum 2004:189). This approach requires fewer assumptions than using either likelihood inference or linear regression.18 It allows me to analyze the effect of changes in the Senate and the president on the distribution of power in the House without requiring any assumptions about the conditional The Fisher’s exact test is also commonly used with small sample sizes, as it doesn’t require any asymptotic assumption. For more on information on Fisher’s exact test see Agresti 1995 and Rosenbaum 2002, chapter 2. 17 The hypergeometric distribution is a discrete probability distribution that describes the number of successes in a sequence of n draws from a finite population without replacement. 18 Furthermore, “Birch (1964) and Cox (1966,1970) show that… [the Fisher exact test] with binary responses posses an optimality property…Specifically, they show that the test statistic…together with the significance level… is a uniformly most powerful unbiased test against alternatives defined in terms of constant odds ratios” (Rosenbaum 2002:31). 16 16 distribution of the dependent variable (changes in the rules and procedures) given the explanatory variable (changes in the Senate and/or president) [these models] impose fewer incidental assumptions. Models for association between an outcome and an explanatory variable bring with them mathematical structure…At a minimum, likelihood based approaches introduce latent variables Pr(Y=1│Z=1) and Pr(Y=1│Z=0), and commonly an entire latent distribution, that of Y│Z, X; this in turn introduces a link function, to translate the linear predictor to the probability scale, and a functional form for the regression of Y on Z and X…each person is assumed to have one latent variable δ(i) which is either 0 if they respond because of the treatment and 1 if their response did not occur because of the treatment. (Bowers and Hansen 2005:6) In my analysis, the units are the 41 Congresses from 1879 until 2001 which are considered constant. The treatment applied to the different units is changes in the partisan balance of the Senate and/or the identity of the president. The binary response is either ri 1 which means that House legislators decided to change rules or procedures or ri 0 meaning that rules and procedures were not changed. The null hypothesis claims that the response of the House is independent of changes in the Senate and/or presidency. The test statistic is the number of Congresses that received the treatment and changed their rules and procedures. The p-value resulting from the Fisher’s exact test is 0.0001. This p-value allows me to reject the null hypothesis that treatment variable has no effect. Substantively, it could mean that changes in the majority of the Senate and/or identity of the president may have an effect on changes in rules and procedures. Under the null hypothesis, the distribution of the different Congresses in the table above would only occur in 0.01% of possible cases if Senate and president were irrelevant. The test casts great doubt on the belief that the 18 constant Congresses that experienced changes in the Senate and/or president changed their distribution of power merely due to chance. These results may suggest that the alternative hypothesis that claims that changes in the Senate and the president can cause radical changes in the distribution of power in the House is plausible. Under this hypothesis, rational House members take into account the 17 preferences of outside institutions like the Senate and the president when deciding issues of power distribution. 4. Bias in Observational studies Could these results be merely due to chance? Is this causal effect believable? Could the results be the product of the influence of an omitted variable? Is there any systematic difference between the ‘constant houses’ that experience changes in the Senate and/or the president and the others that do not? If confounders exist, are they driving the results? When working with observational data, one of the central concerns of researchers is that treatments may be assigned to subjects in a biased manner: “An observational study is biased if the treated and control groups differ prior to treatment in ways that matter for the outcome under study” (Rosenbaum 2002:71). To reduce the probability that the treated and control groups are different in substantive ways, scholars attempt to control for both overt and hidden bias. Overt bias refers to the probability that the result is generated by differences between treated and control groups before the treatment is applied, through variables that were observed. Hidden bias refers to the bias introduced by variables that were unobserved. Addressing both types of bias is crucial, since if “relevant variables are omitted, our ability to estimate causal inferences correctly is limited” (King, Keohane, and Verba 1994:174). Investigators seeking to avoid omitted variable bias typically include ‘control’ variables that are correlated with the dependent and independent variables. Recently investigators have also turned to matching and stratification to combat bias. By using these techniques, the differences between groups that receive the treatment and those that do not in specific covariates are removed. However, “even after adjustments have been made for observed covariates (i.e. characteristics that were measurable prior to treatment assignment), estimates of treatment effect can still be biased by imbalances in unobserved covariates.” (Rosenbaum 1984:41, emphasis mine). A less common tool for checking biases is sensitivity analysis. In contrast to control 18 variables and matching, sensitivity analysis19 asks: “How large would the effect of unobserved confounders need to be to explain the observed association?” The result of the analysis is a quantitative measure of uncertainty based on the data that assesses both types of bias. In the next section, I analyze both the overt and hidden bias present in my model. First, I examine different covariates suggested by previous literature to be important in causing changes in rules and procedures in the House. In particular, I stratify the data by the identity of the majority party and conduct a test similar to the test above. Second, I address hidden bias by conducting sensitivity analysis. 1. Controlling for Overt Bias As mentioned above, to assume that the influence of observed covariates is zero is to assume a priori all Congresses are equally likely to change their rules and procedures when faced with changes in the Senate or president. My test would be incorrect if constant Houses that experience changes in the Senate and/or president and those that did not, differ prior to treatment in ways that are important for the outcome under investigation. If overt bias is present,20 we can adjust the data with several techniques like multivariate regression, matching or stratification: “the first step is to adjust for observed covariates, to compare subjects who appear similar in terms of observed covariates prior to treatment” (Rosenbaum 2004:153). As a result, we can account for the differences between constant Houses by matching them or dividing the Houses into stratums depending on the values of the covariates. Which are important confounds in the congressional literature? As mentioned above, Traditional Theories of legislative organization claim that changes in the preferences of House members trigger institutional reforms. That is, when the House experiences significant changes “Cornfield et al (1959) contains the first sensitivity analysis in an observational study, replacing the qualitative statement that ‘association does not imply causation’ by a quantitative statement about the magnitude of hidden bias that would need to be present to explain away the observed association between treatment and response” (Rosenbaum 2004b:1). 20 “Overt bias is one that can be seen in the data at hand” Rosenbaum 2002:71). 19 19 either in the identity of its majority party or in the ideological position of its members, then redistribution of power should be more likely. This literature suggests that the identity of the majority party and ideological preferences of House members (as measured by DW-NOMINATE scores) are significantly related to changes in the rules and procedures of the House (Schickler 2001). In what follows I stratify the data to determine whether controlling for majority party alters the relationship between changes in the Senate and/or president and changes in institutions.21 Table 4 presents the data for 41 constant Houses stratified by majority party. The stratification allows the relationship between treatment and result to be compared among Congresses that are homogeneous in the identity of the majority party. Is the relationship between House rules and exogenous actors affected by whether the majority belongs to the Democratic or Republican Party? TABLE 4: Exact Stratification on Majority Party Democratic Majority Republican Majority Rules ~ Rules S/P 14 3 ~ S/P 5 8 S/P 4 1 ~ S/P 2 4 To learn whether a difference exists between treated and controlled Congresses on this covariate, I employed the Mantel-Haenszel test, which is analogous to Fisher’s exact test in cases 21 I decided to not include a control variable for ideology based on DW-NOMINATE. As explained above, ideology scores are derived from roll call votes. But votes on the floor are the product of the agenda set by legislators who are given power by rules and procedures. As a result, these scores would have been endogenously determined by my dependent variable, changes in the distribution of power in the House. In section 5, I conduct robustness tests on the dependent variable using DW-NOMINATE scores, to check how robust the results are to different measures of the dependent variable. 20 with more than 1 stratum (i.e. 2 x 2 x S contingency tables). The test statistic is again the number of positive responses among units that have received the treatment across all strata. The p-value of the test statistic is 0.01. This small p-value implies that the results found in the previous section are not an artifact of which party controls the House. 2. Assessing the Impact of Hidden Bias Unmeasured covariates may still create biased estimates. Sensitivity analysis in this case is very informative as it shows how large the effect of the unobserved variables would need to be to alter the results. Sensitivity analysis asks: “How would inferences about treatment effects be altered by hidden biases of various magnitudes?... How large would these differences have to be to alter the qualitative conclusions of a study?” (Rosenbaum 2002:106). Most statistical analyses implicitly assume the absence of hidden bias. “In many empirical studies of the effect of social program researchers assume that, conditional on a set of observed covariates, assignment to the treatment is exogenous or unconfounded (aka selection on observables). Often this assumption is not realistic, and researchers are concerned about the robustness of their results to departures from it” (Imbens 2003:126). How would my results change if we relaxed the assumption of exogeneity? Sensitivity analysis provides a quantitative answer: Sensitivity analysis is conceptually related to the practice of assessing sensitivity of estimates by comparisons with results obtained by discarding one or more observed covariates…The attraction of the sensitivity analysis is that it is more directly relevant: one is not interested in what would have happened in the absence of covariates actually observed, but in biases that are the result from not observing all relevant covariates. (Imbens 2003: 126) How does sensitivity analysis work? “The sensitivity model assumes the following: in the population…treatments were assigned independently, and two subjects…may differ in their odds of receiving the treatment, pr(Z=1)/pr(Z=0), by at most a factor of 1 .” (Rosenbaum 2004:155). Suppose we have two different Houses, (j) and (k), where the identity of the majority 21 party from one Congress to the next one is similar and the relative size of the factions in the majority party is equivalent. The odds that that these two ‘constant’ Houses experience an effect coming from changes in the Senate and the president are j 1 j and k and the odds 1 k ratio is the ratio of these odds: 1 j (1 k ) j , k with k (1 j ) x j xk . (1.1) Sensitivity analysis shows the number 1 that shows the ratio of those odds. When equals 1, then the study is free of hidden bias and we can proceed in the analysis as if changes in the Senate and president were randomly assigned to different constant congresses. However, if 2 , then those two Congresses could differ in their odds of experiencing the treatment by as much as a factor of 2: one Congress is twice as likely as the other to receive the treatment: is a measure of the degree of departure from a study that is free of hidden bias. A sensitivity analysis will consider several possible values of Γ and show how the inferences might change. A study is sensitive if values of Γ close to 1 could lead to inferences that are very different from those obtained assuming the study is free of hidden bias. A study is insensitive if extreme values of Γ are required to alter the inference. (Rosenbaum 2002:107) The model (1.1) can be re-written in terms of an unobserved covariate u: Congress j has an unobserved covariate u j . “Then the model has two parts, a logit form linking treatment assignment j to the covariates (u j ) and a constraint on u j ” (Rosenbaum 2002:107). j log 1 j u j , with 0 u j 1, (1.2) where is an unknown parameter. If we have two Congresses, j and k, the ratio of the odds that both Congresses receive the treatment is: 22 j 1 k exp u j u k k 1 j Therefore, if two units…differ in their odds of receiving the treatment by a factor that involves the parameter and their difference in their unobserved covariates u…sensitivity analysis will display the sensitivity of inferences to a range of assumptions about (γ, u). Specifically, for several values of γ, the sensitivity analysis will determine the most extreme inferences that are possible for u satisfying the constraint in (1.2). (Rosenbaum 2002:108, 110) “If conclusions are insensitive over a range of plausible assumptions about u, the number of interpretations of the data is reduced, and causal conclusions are more defensible” (Rosenbaum and Rubin 1983:213). How is sensitivity analysis conducted in this framework? For a range of Γ 1, we need to find the upper and lower bounds on inference quantities, like p-values (or endpoints of confidence intervals). We need to report these p-values for several values of Γ until the conclusion begins to change. “For several values of Γ, the sensitivity analysis computes the maximum possible values of the significance level…For Γ = 1, there is only one possible significance level, namely the usual one from randomization test…Sensitivity analyses for tests are inverted to yield confidence intervals” (Rosenbaum 2004:156) How large must Γ be, that is, how far must Γ depart from the randomization distribution, to alter materially the conclusions of the study? Table 5 shows the upper and lower bounds of significance levels for different values of Γ.22 TABLE 5. Sensitivity analysis. Range of Significance levels for the Fisher Exact Test. Γ 1 2 3 4 22 Minimum < 0.0001 < 0.0001 < 0.0001 < 0.0001 Maximum < 0.0001 0.006 0.035 0.09 The full results may be obtained from the author upon request. 23 In the case Γ = 3, the significance level might be less than 0.0001 or it might be as high as 0.035, but for all unobservable variables the null hypothesis of no effect of changes in the Senate and/or president on decisions to change the rules and procedures of the House is implausible. The null hypothesis fails to reach conventional statistical levels for implausibility when Γ 4. So, to attribute the observed pattern of change in the distribution of power in the House to an unobserved covariate rather than to an effect of changes in the Senate and/or the president, that unobserved covariate would need to produce a fourfold increase in the odds of changes in the Senate and/or the president and it would need to be a near perfect predictor of decisions to change rules and procedures. Furthermore, this unobserved covariate u would have to more than quadruple the odds of changes in the Senate and the presidency and more than quadruple the odds of changes in the distribution of power in the House, before altering the conclusion that Houses tend to change their distribution of power after changes in the presidency and the Senate. The difference between Congresses that experience changes in the preferences of the Senate and/or the president and those that do not does not seem to be easily explained as the result of an imbalance due the existence of unobserved covariates. 5. Robustness tests Do my results depend on the operationalization of the concept “constant Congresses”? In this section I assess whether my results are contingent on my definition of “constant House.” Throughout the paper, I considered a House constant when (1) the majority party from one Congress to the next is the same and (2) the relative size of the factions of the majority party is similar. In what follows I will first relax condition 2 and analyze the model including all Houses where the relative size of its factions changed across consecutive congressional terms. Second, I will use a totally different operationalization of the variable “constant House.” Specifically, I will 24 use DW-NOMINATE scores to define which Houses are ‘constant’ across consecutive congressional terms. 1. Robustness test for the ‘constant’ House variable First, I relax the definition of constant House and include all Congresses whose majority party did not change from one Congress to the next in the following 2x2 contingency table.23 Thus Table 6 encompasses more Congresses than the previous analysis since it includes Congresses where the relative size of party factions changed. TABLE 6. Robustness test for the “constant’ House variable. in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House in Rules 20 (77%) ~ in Rules 6 (23%) Total 26 (100%) 9 (40%) 13 (60%) 22 (100%) The table shows that more than 77% of the 26 Houses that experienced changes in the Senate and/or president did change their distribution of power even though their membership remained constant. Of the 22 Houses that did not experience changes in the Senate and/or president, 60% did not change their rules and procedures. Traditional Theories would never predict such significant differences across rows in each column (p-value 0.001, from Fisher’s exact test). If the data supported extant theories of legislative organization, then for Houses that either decided or not to change their distribution of power, we shouldn’t see differences between situations where the Senate and/or president changed and those where they did not. This difference is predicted by the Constitutional Theory but is difficult to explain using the conventional models. Again, we can reject the null hypothesis that decisions to rearrange distributions of power in the House are independent of changes in the Senate and/or the president. 23 The additional Congresses included in this analysis are the following: 55 th, 59th, 60th, 73rd, 78th, 79th and 82nd. 25 Thus the results obtained in the previous section are robust to a different operationalization of the variable “constant Congress.” 2. Robustness test using DW-NOMINATE scores To further test the robustness of the ‘House constant’ definition, I decided to conduct tests using the DW-NOMINATE24 scores employed by congressional researchers. Using this variable, when the score for the median member of the House (or the party) changes substantially, the new House is considered significantly different from the previous one. Applying this definition to my analysis, those Houses that experience a “substantial change” in the scores of the median member of the House and majority party cannot be considered constant from one congressional period to the next one. But what is a “substantial change”? As there is no answer to this question in the literature, I decided to use different definitions of “substantial” change. Specifically, I computed the differences in contiguous Congresses25 between the median member of the House and the median member of the majority party26 in the first and second dimension.27 The table (Table 2 in the Appendix) shows the movement in the median of the House and the median of the majority party from one Congress to the next. However, how large should the magnitude be to consider it substantial? What is the threshold below which a House is considered constant? Rather than selecting a threshold ad hoc, I tested several plausible values. Each threshold took the form, “If the difference in one of the medians in one of the dimensions is X, then that Congress cannot be considered constant and is not included in the analysis,” with “DW nominate is a dynamic version of W-Nominate and is very similar to the original D-Nominate procedure. The only differences is that DW-Nominate is based on normally distributed errors rather than on logit errors and that each dimension has a distinct (salience) weight (the weight for the first dimension is always 1.0)” (http://voteview.com/pmediant.htm). 25 DW-Nominate scores in one Congress are directly comparable with scores in another Congress (http://voteview.com/pmediant.htm). 26 Both measures of the median were taken from Poole’s website: http://voteview.com/pmediant.htm. 27 The first dimension refers to economic issues. The second refers to the north-south split between 1930 and 1970’s. 24 26 X 0.10, 0.15, 0.20, 0.25 . Tables 7 through 10 present the distributions resulting from each threshold, along with the results of a Fisher’s exact test. The small p-value produced in every case provides further evidence that the effect of the Senate and the president on House rules is not an artifact of variable coding. TABLE 7. Cutting point 0.1. Probability that the null hypothesis of no effect is true: 0.01 (from Fisher’s exact test) in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House in Rules 14 (88%) ~ in Rules 3 (18%) Total 17 (100%) 5 (33%) 10 (67%) 15 (100%) TABLE 8. Cutting point 0.15. Probability that the null hypothesis of no effect is true: 0.05 (from Fisher’s exact test) in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House in Rules 14 (74%) ~ in Rules 5 (26%) Total 19 (100%) 8 (40%) 12 (60%) 20 (100%) TABLE 9. Cutting point 0.2. Probability that the null hypothesis of no effect is true: 0.01 (from Fisher’s exact test) in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House in Rules 18 (78%) ~ in Rules 5 (22%) Total 23 (100%) 8 (40%) 12 (60%) 20 (100%) 27 TABLE 10. Cutting point 0.25. Probability that the null hypothesis of no effect is true: 0.008 (from Fisher’s exact test) in Senate and /or president, ~ in House ~ in Senate and /or president, ~ in House 6. in Rules 20 (80%) ~ in Rules 5 (20%) Total 25 (100%) 9 (41%) 13 (59%) 22 (100%) Conclusion The chapter shows that the House does not need a single member to change her preferences to alter its organizational arrangement. By examining institutional changes adopted in the US House from 1879 until 2001, I showed that whenever House members face a new bargaining situation caused by changes in the Senate and/or the president, they are far more likely to modify their organizational arrangements. There is a significant difference between the proportion of Houses that redistribute power among its members immediately following a change in the Senate or the president and the proportion that do it when no such change occurs. By studying major rule changes in House procedures over several decades, I have shown that holding constant House member preferences, changes in the identity of the president and/or the composition of the Senate has regularly been followed by radical alterations of the distribution of power in the House in ways that my theory predicts but the conventional wisdom does not. This paper suggests that analyses of the internal dynamics of the House need to incorporate exogenous factors such as the president and the Senate. The incorporation of these factors produces new insights regarding the timing and causes of legislative organization that Traditional Theories do not provide. While Traditional Theories predict no difference between the number of Houses that would embark on significant rule changes after changes in the Senate 28 and/or president have occurred or not, the results show that substantial differences exist. The Constitutional Theory helps us understand this result by incorporating into the analysis the preferences of exogenous institutions like the Senate and the presidency. Furthermore, these results have both normative and practical implications. Normatively, the implications are critical to the notion of representation. If policy outcomes are closely tied to the distribution of power, then knowing which actors are powerful allows us to know precisely which interests are privileged. In addition, the ability to predict changes in the distribution of power has significant practical implications for group representation. Groups attempting to influence policy in Washington need to know where they should invest their scarce resources. If return on investment depends on the ability to affect legislation, an investment strategy should be based on a coherent understanding of how the House distributes power among its members and the conditions under which it will change its power sharing agreements. Such knowledge could dictate when it would be wise for social interest groups to change their lobbying strategies. In conclusion, I find that the constitutional requirement to bargain with non-House actors can induce House members to make different leadership decisions than they would if they were, as commonly represented, an isolated entity unaware of other chambers or branches of government. 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