Social Research Methods: Qualitative and Quantitative Approaches

QUALITATIVE AND QUANTITATIVE MEASUREMENT

Discriminant validityis the opposite of con-
vergent validity and means that the indicators of one
construct “hang together,” or converge, but also are
negatively associated with opposing constructs.
Discriminant validity says that if two constructs A
and Bare very different, measures of Aand Bshould
not be associated. For example, I have ten items that
measure political conservatism. People answer all
ten in similar ways. But I also put five questions that
measure political liberalism on the same question-
naire. My measure of conservatism has discrimi-
nant validity if the ten conservatism items converge
and are negatively associated with the five liberal-
ism ones. (See Figure 5 for a review of measure-
ment validity.)

Reliability and Validity
in Qualitative Research

Qualitative research embraces the core principles of
reliability and validity, but we rarely see the terms in
this approach because they are so closely associated
with quantitative measurement. In addition, in qual-
itative studies, we apply the principles differently.

Reliability.Recall that reliabilitymeans depend-
ability or consistency. We use a wide variety of tech-
niques (e.g., interviews, participation, photographs,
document studies) to record observations consis-
tently in qualitive studies. We want to be consistent
(i.e., not vacillating or being erratic) in how we make
observations, similar to the idea of stability reliabil-
ity. One difficulty with reliability is that we often
study processes that are unstable over time. More-
over, we emphasize the value of a changing or
developing interaction between us as researchers
and the people we study. We believe that the subject
matter and our relationship to it is an evolving
process. A metaphor for the relationship is one of an
evolving relationship or living organism (e.g.,
a plant) that naturally matures over time. Many qual-
itative researchers see the quantitative approach to

reliability as a cold, fixed mechanical instrument that

one applies repeatedly to static, lifeless material.

In qualitative studies, we consider a range of

data sources and employ multiple measurement

methods. We do not become locked into the

quantitative-positivist ideas of replication, equiva-

lence, and subpopulation reliability. We accept

that different researchers or researchers who use

alternative measures may find distinctive results.

This happens because data collection is an inter-

active process in which particular researchers oper-

ate in an evolving setting whose context dictates

using a unique mix of measures that cannot be

repeated. The diverse measures and interactions

with different researchers are beneficial because

they can illuminate different facets or dimensions

of a subject matter. Many qualitative researchers

question the quantitative researcher’s quest for stan-

dard, fixed measures and fear that such measures

ignore the benefits of having a variety of researchers

with many approaches and may neglect key aspects

of diversity that exist in the social world.

Validity.Validitymeans truthfulness. In qualitative

studies, we are more interested in achieving au-

thenticity than realizing a single version of “Truth.”

Authenticitymeans offering a fair, honest, and bal-

anced account of social life from the viewpoint of

the people who live it every day. We are less con-

cerned with matching an abstract construct to em-

pirical data than with giving a candid portrayal of

social life that is true to the lived experiences of the

people we study. In most qualitative studies, we em-

phasize capturing an inside view and providing a

detailed account of how the people we study un-

derstand events (see Expansion Box 2, Meanings of

Validity in Qualitative Research).

There are qualitative research substitutes for the

quantitative approach to validity: ecological validity

or natural history methods. Both emphasize convey-

ing an insider’s view to others. Historical researchers

use internal and external criticisms to determine

whether the evidence is real. Qualitative researchers

adhere to the core principle of validity, to be truthful

(i.e., avoid false or distorted accounts) and try to cre-

ate a tight fit between understandings, ideas, and

statements about the social world and what is actu-

ally occurring in it.

Discriminant validity A type of measurement valid-

ity for multiple indicators based on the idea that indi-

cators of different constructs diverge.