Asking Questions - The Definitive Guide To Questionnaire Design ...

GLOSSARY 365
idation also has the special meaning of recontacting the respondent
to determine whether the interview was actually conducted.
validity A valid measure is one that measures what it claims to and
not something else. The concept is clearest with respect to behavioral
questions, where an outside validation source is possible.
Nevertheless, various researchers have proposed validity measures
for attitudinal items. Validity is a continuous concept and refers to
the distance between the measure and a completely valid measurement.
It is the converse of response bias. (See also bias.)
VALS (from values and lifestyles) One of the more widely known
psychographic segmentation research programs. It is conducted by
SRI Consulting and attempts to show more general psychographic
segments that are relevant and can be used across a wide number of
people and topics. Their psychographic approach sorts people into
one of eight different groups. (See Chapter Eight.)
variability, variance As used with a population, variability refers to
differences between individuals or groups in the population, usually
measured as a statistical variance or simply by observing the differences
between the measurements for the group. As used with attitudes,
variability refers to the sensitivity of responses to differences
in question wording or context. For samples, variance or variability
refers to differences between repeated samples selected from the
same population using the same survey procedures. For statistical
definitions of variance, see any statistics textbook.
variables See dependent, independent, and interdependent variables.