Total Survey Error: Past, Present, and Future Robert M. Groves U.S. Census Bureau Lars Lyberg Statistics Sweden and Stockholm University 1 Outline 1. 2. 3. 4. Evolution of “total survey error” (TSE) Weaknesses of the TSE framework Strengths of the TSE framework Future of surveys and research agenda ideas 2 Deming (1944) “On Errors in Surveys” • American Sociological Review! • First listing of sources of problems, beyond sampling, facing surveys • The 13 factors 3 Deming’s 13 factors -The 13 factors that affect the usefulness of a survey -To point out the need for directing effort toward all of them in the planning process with a view to usefulness and funds available -To point out the futility of concentrating on only one or two of them -To point out the need for theories of bias and variability that correlate accumulated experience 4 5 Comments on Deming (1944) • Does include nonresponse, sampling, interviewer effects, mode effects, various other measurement errors, and processing errors • Omits coverage errors • Includes nonstatistical notions (auspices) • Includes estimation step errors (wrong weighting) • “Total survey error” not used as a term 6 Sampling Text Treatment of Total Survey Error • Kish, Survey Sampling, 1965 – Graphic on biases – 65 of 643 pages on various errors, with specified relationship among errors 7 Frame biases Sampling Biases “Consistent” Sampling Bias Constant Statistical Bias Noncoverage Nonobservation Nonresponse Field: data collection Nonsampling Observation Office: processing Biases 8 Sampling Text Treatment of Total Survey Error • Särndal, Swensson, Wretman, Model Assisted Survey Sampling, 1992 – Part IV, 124 pp. of 694, coverage, nonresponse, measurement error; omits processing error • Lohr, Sampling Design and Analysis, 1999 – 34 of 500 pages, nonresponse, randomized response 9 Other textbooks • Cochran (1953). Sampling Techniques. 40 pages in concluding chapter on “sources of error in surveys” • Deming (1950). Some Theory of Sampling. Starts with the 1944 factors but then continues with pure sampling • Hansen, Hurwitz and Madow (1953). Sample Survey Methods and Theory, Vol 1. Nine pages on survey errors. • Zarkovich 1966. Quality of Statistical Data. 10 Total Survey Error (1979) Anderson, Kasper, Frankel, and Associates • Empirical studies on nonresponse, measurement, and processing errors for health survey data • Initial total survey error framework in more elaborated nested structure 11 Sampling Variable Error Field Nonsampling Processing Frame Total Error Sampling Consistent Noncoverage Bias Nonobservation Nonsampling Nonresponse Field Observation 12 Processing Survey Errors and Survey Costs (1989), Groves • Attempts conceptual linkages between total survey error framework and – psychometric true score theories – econometric measurement error and selection bias notions • Ignores processing error • Highest conceptual break on variance vs. bias • Second conceptual break on errors of nonobservation vs. errors of observation 13 Mean Square Error construct validity theoretical validity empirical validity reliability Variance Errors of Nonobservation Coverage Nonresponse Observational Errors Sampling Interviewer Respondent Instrument Mode criterion validity - predictive validity - concurrent validity Bias Observational Errors Errors of Nonobservation Coverage Nonresponse Sampling Interviewer Respondent Instrument14 Mode Nonsampling Error in Surveys (1992), Lessler and Kalsbeek • Evokes “total survey design” more than total survey error • Omits processing error 15 Components of Error Frame errors Topics Missing elements Nonpopulation elements Unrecognized multiplicities Improper use of clustered frames Sampling errors Nonresponse errors Deterministic vs. stochastic view of nonresponse Unit nonresponse Item nonresponse Measurement errors Error models of numeric and categorical data Studies with and without special data collections 16 Introduction to Survey Quality, (2003), Biemer and Lyberg • Major division of sampling and nonsampling error • Adds “specification error” (a la “construct validity”) or relevance error • Formally discusses process quality • Discusses “fitness for use” as quality definition 17 Sources of Error Types of Error Specification error Concepts Objectives Data element Frame error Omissions Erroneous inclusions Duplications Nonresponse error Whole unit Within unit Item Incomplete Information Measurement error Information system Setting Mode of data collection Respondent Interview Instrument Processing error Editing Data entry Coding Weighting Tabulation 18 Survey Methodology, (2004) Groves, Fowler, Couper, Lepkowski, Singer, Tourangeau • Notes twin inferential processes in surveys – from a datum reported to the given construct of a sampled unit – from estimate based on respondents to the target population parameter • Links inferential steps to error sources 19 Representation Measurement Inferential Population Construct Validity Target Population Measurement Sampling Frame Measurement Error Response Sample Processing Error Coverage Error Sampling Error Nonresponse Error Edited Data Respondents Survey Statistic 20 Key Statistical Developments in Total Survey Error 1 • • • • • Errors of observers can be correlated (1902), Karl Pearson Interpenetrating samples (1946), Mahalanobis Criteria for true values (1951), Hansen, Hurwitz, Marks and Mauldin Essential survey conditions, correlated response variance (1959), H-H-Bershad BC survey model “mixed-error model”(1961), H-H-B 21 Key Statistical Developments in Total Survey Error 2 • Interviewer effects using ANOVA (Kish 1962) • Simple response variance via reinterviews (1964), H-HPritzker • Relaxed assumptions of zero covariance of true values and response deviations (1964, 1974), Fellegi • Errors of Measurement (1968), Cochran • Estimating model components via basic study schemes using replication, interpenetreation and combinations of the two (1969), Bailar and Dalenius • Estimating nonsampling variance using mixed linerar models (1978), Hartley and Rao • “Error Profile” of Current Population Survey (1978), Brooks and Bailar • Multi-method multi-trait models on survey measures 22 (1984), Wothke…Browne Key Statistical Developments in Total Survey Error 3 • Measurement of imputation error variance through multiple imputation (1987), Rubin • Total error model for PES (1991), Mulry and Spencer • Measurement Errors in Surveys (1991) Section (Biemer and Stokes..Colm..Fuller and others – attempts to juxtapose psychometric notions with survey statistical notions of measurement error • Latent class model applications to survey errors (late 1990’s), Biemer, Tucker and others • Measurement error effects on analysis (1997) Biemer and Trewin 23 Key Statistical Developments in Total Survey Error 4 • Certain components understudied – – – – • • coverage error variance nonresponse error variance all processing errors biases in general The movement from measurement of MSE to CBM, SOP thereby getting a situation where Var becomes an approximation of MSE (errorfree processes) Simultaneous treatment of more than one error source (ITSEW) 24 Summary of the Evolution of “Total Survey Error” • Roots in cautioning against sole attention to sampling error • Framework contains statistical and nonstatistical notions • Most statistical attention on variance components, most on measurement error variance • Late 1970’s attention to “total survey design” (methods and theory for resource allocation to the control of various sources of error • 1980’s-1990’s attempt to import psychometric notions, CASM 25 • Key omissions in research Weaknesses of the Common Usage of “Total Survey Error” – – – – – – Notably a user perspective is missing Key quality dimensions are missing in the TSE paradigm User often cannot or prefers not to question accuracy The complexity does not invite outside scrutiny of accuracy Users not really informed about real levels of error or uncertainty We don’t really know how users perceive information on errors 26 Other Weaknesses of the Total Survey Error Paradigm 1 1. Lack of routine measurements No agency does this Error/quality profiles are useful but rare 2. Ineffective influence on professional standards Little expansion beyond sampling error in practice Press releases on Federal statistics rarely contain even sampling errors Survey error research compartmentalized rather than integrated Methodologists tend to specialize Root causes of error often still missing How about OMB’s requirement of NR bias studies if NR expects to exceed 20%? 27 Other Weaknesses of the Total Survey Error Paradigm 2 3.Large burden on design of some estimators Interpenetration, reinterviews for variance estimation complicated and costly Intractable expressions for some components 4. Some assumptions unrealistic 28 Strengths of the Total Survey Error Framework 1. Taxonomic decomposition of errors • nomenclature for different components 2. Separation of phenomena affecting statistics in different ways • variance vs. bias; observation vs. nonobservation; respondent/interviewer/measurement task; processing 3. Conceptual foundation of the field of survey methodology • subfields defined by errors 4. Tool to identifying gaps in the research literature • e.g., where are the error evaluation papers on processing? 29 Needed Steps in a Research Agenda for Total Survey Error 1 1. Integrating causal models of survey errors • cognitive psychological mechanisms (anchoring, recall decay) 2. Research on interplay of two or more error sources jointly • e.g., nonresponse and measurement error 3. Research on the interplay of biases and variances • e.g., does simple response variance increase accompany some response bias reductions (selfadministration effects)? 30 Needed Steps in a Research Agenda for Total Survey Error 2 Guidance on tradeoffs between quality measurement and quality maximization and between measures and developing error-free processes - how much should we spend on quality enhancement vs. measurement of quality (Spencer, 1985)? 5. Integrating other notions of quality into the total survey error paradigm - if “fitness for use” predominates as a conceptual base, how can we launch research that incorporates error variation associated with different uses? Australian Bureau of Statistics 4. 31 Needed Steps in a Research Agenda for Total Survey Error 3 6. Exploiting a multiple-mode, multiple frame, multiple phase survey world 7. Need for methodological studies to assist the user 8. Costs and risks 9. Develop theories for optimal design of specific operations, design principles 10. More standards? 32