Social Research Methods: Qualitative and Quantitative Approaches

QUALITATIVE AND QUANTITATIVE MEASUREMENT

things we do at particular times and places. Valid-
ity is part of a dynamic process that grows by accu-
mulating evidence over time, and without it, all
measurement becomes meaningless.
Some researchers use rules of correspondence
(discussed earlier) to reduce the gap between ab-
stract ideas and specific indicators. For example, a
rule of correspondence is: A teacher who agrees
with statements that “things have gotten worse at
this school in the past 5 years” and that “there is little
hope for improvement” is indicating low morale.
Some researchers talk about the epistemic correla-
tion,a hypothetical correlation between an indica-
tor and the construct that the indicator measures. We
cannot empirically measure such correlations, but
they can be estimated.^9

Four Types of Measurement Validity.

1. Face validityis the most basic and easiest
   type of validity to achieve. It is a judgment by the

scientific community that the indicator really mea-

sures the construct. It addresses the question: On the

face of it, do people believe that the definition and

method of measurement fit? For example, few

people would accept a measure of college student

math ability by asking students what 2 + 2 equals.

This is not a valid measure of college-level math

ability on the face of it. Recall that the principle of

organized skepticism in the scientific community

means that others scrutinize aspects of research.^10

2. Content validityaddresses this question: Is
   the full content of a definition represented in a mea-
   sure? A conceptual definition holds ideas; it is a
   “space” containing ideas and concepts. Measures
   should sample or represent all ideas or areas in the
   conceptual space. Content validity involves three
   steps. First, specify the content in a construct’s def-
   inition. Next, sample from all areas of the definition.
   Finally, develop one or more indicators that tap all
   of the parts of the definition.
   Let us consider an example of content validity.
   I define feminismas a person’s commitment to a set
   of beliefs creating full equality between men and
   women in areas of the arts, intellectual pursuits,
   family, work, politics, and authority relations. I cre-
   ate a measure of feminism in which I ask two sur-
   vey questions: (1) Should men and women get equal
   pay for equal work? and (2) Should men and women
   share household tasks? My measure has low con-
   tent validity because the two questions ask only

Face validity A type of measurement validity in

which an indicator “makes sense” as a measure of a

construct in the judgment of others, especially in the

scientific community.

Content validity A type of measurement validity

that requires that a measure represent all aspects of

the conceptual definition of a construct.

TABLE 1 Summary of Measurement Reliability and Validity Types

RELIABILITY (DEPENDABLE MEASURE) VALIDITY (TRUE MEASURE)

Stability—over time
(verify using test-retest method)

Face—makes sense in the judgment of others

Representative—across subgroups
(verify using split-half method)

Content—captures the entire meaning

Equivalence—across indicators
(verify using subpopulation analysis)

Criterion—agrees with an external source

Concurrent—agrees with a preexisting measure

Predictive—agrees with future behavior

Construct—has consistent multiple indicators

Convergent—alike ones are similar

Discriminant—different ones differ