Measurement I. Knowing a Good
Measure When You See It.
Conceptual and operational definitions of
a variable
An example: voter turnout in the U.S.
Measurement error and validity
Conceptual Definitions - 1

A conceptual definition of a variable states
precisely what you mean when you use a
particular term.

A society that “supports democracy” is one
that emphasizes tolerance, trust, political
activism, and Post-Materialist values, not just
one that pays lip service to the ideals of
democracy. -- Ronald Inglehart
Conceptual Definitions - 2

A good conceptual definition:
Looks at how other scholars have defined a
term, and goes with the consensus unless
there is a good reason to deviate.
 Allows you to test the theory that you want
to test.
 Is not circular (for example, does not say
that support for democracy is when the
public voices support for democratic values)

Operational Definitions

An operational definition of a variable is
a complete recipe for going out into the
world and measuring a variable.
It helps us make the leap from our
subjective impressions to an objective
measure.
 Like a recipe in any good cook book, a good
operational definition can be followed by
any other chef.

Operational Definitions

To measure “support for democracy,”
Inglehart uses the World Values/
European Values Survey from 1995-97
and 1999-2001 and looks at average
levels of agreement with nine statements
such as:

“Is it good to have a strong leader who does
not have to bother with parliament and
elections?”
Voter Turnout in the U.S.:
Measure 1

Conceptual: “Turnout” is the percentage of
those who can vote who actually do.

The traditional operational definition is:
TotalVotesCast
Turnout 
VotingAgePopulation
Where Voting Age Population (VAP) includes
noncitizens and convicted felons, but not citizens
living overseas.
Voter Turnout in the U.S.:
Using Measure 1
Voter Turnout in Presidential Elections
(% of Voting Age Population)
70
50
40
30
20
10
0
19
48
19
52
19
56
19
60
19
64
19
68
19
72
19
76
19
80
19
84
19
88
19
92
19
96
20
00
Turnout Rate
60
Year
Voter Turnout in the U.S.–
Measure 2

Conceptual: “Turnout” is the percentage of
those who can vote who actually do.
TotalVotesCast
Turnout 
VotingElig iblePopula tion
Where Voting Eligible Population is purged of
noncitizens and convicted felons but includes
citizens living overseas.
Voter Turnout in the U.S.:
Measures 1 and 2
70
Voting Age
Population
Turnout %
60
Voting Eligible
Population
Turnout %
50
40
30
20
10
0
Year 1948 1952 1956 1960 1964 1968 1972 1976 1980 1984 1988 1992 1996
Measurement Validity
Measurement Validity is highest
when the gap between your
conceptual definition and your
operational definition is smallest.
Measurement Error
Measured Value =
True Value + Bias + Random Error
Sources of Bias:
1. “Response Bias:” survey respondents lie
2. Faulty instruments: scale is always off,
question wording always bad.