Page 563 - Encyclopedia of Nursing Research

530 n VALIdITy

instrument be used as a criterion. A true cri- analysis and related factor analytic proce-
terion is usually a widely accepted standard dures, such as latent variable modeling. Factor
V of the concept of interest. Few of these exist analysis has become one of the major ways in
within the areas of interest to nursing. which nursing researchers examine the con-
Construct validity has become the central struct validity of an instrument. It is impor-
type of validity assessment. It is now thought tant to note that this approach addresses
that construct validity really subsumes all only the second aspect of construct validity
other forms. In essence, construct valida- testing and in itself is insufficient to support
tion is a creative process that rarely achieves the validity of an instrument. Factor analysis
completion. Instead, each piece of evidence simply provides evidence that the underly-
adds to or detracts from the support of con- ing factor structure of the instrument is in
struct validity, which builds with time and line with the theoretically determined struc-
use. Nunnally (1978) proposes three major ture of the construct.
aspects of construct validity: (a) specifica- The third aspect of construct validation
tion of the domain of observables; (b) extent provides an opportunity for more creative
to which the observables tend to measure approaches to testing. Hypotheses proposed
the same concept, which provides a bridge have to do with the relationship of the con-
between internal consistency, reliability, and cept being measured with other concepts that
validity; and (c) evidence of theoretically have established methods of measurement.
proposed relationships between the measure These hypotheses deal with convergent and
and predicted patterns. The first aspect is discriminate construct validity, subtypes
similar to content validity and is essentially that examine the relationship of the concept
handled through formalized concept clarifi- under study with similar and dissimilar
cation in instrument development. The inclu- concepts. If data shows a strong relationship
sion of this specification of the domain under with similar concepts and no relationship
construct validity supports the contention with dissimilar concepts, evidence is built
that construct validity is the primary form, for the construct validity of the instrument.
with other types forming subsets within its Should data not support similarities and
boundaries. differences, several options are possible: (a)
The other two aspects of construct valid- the instrument under construction may not
ity are examined formally through a series be accurately measuring the concept, (b) the
of steps. These steps form a hypothesis- instruments for the other concepts may be
testing procedure in which the hypotheses faulty, or (c) the theory on which the test-
are based on the theoretical underpinnings ing was based upon may be inaccurate. The
of the instrument. Hypotheses can relate multitrait–multimethod matrix has been pro-
to the internal structure of the items on the posed as a way to formally test convergent
instrument. Hypotheses can also refer to the and discriminate construct validity.
instrument’s anticipated relationship with Another approach to examining the
other concepts, based on a theoretical formu- relationship among concepts involves a
lation. The first set of hypotheses fall into the known group technique. In this method,
second aspect of construct validity testing; the researcher hypothesizes that the instru-
the latter relate to the third aspect. ment will provide a certain level of data from
Although there are no formalized groups with known levels on the concept the
ways to examine the hypothesis proposed instrument has been designed to measure.
for construct validity testing, some typical The above approaches to testing con-
approaches have been identified in nursing struct validity are only samples of tech-
research. Primarily, the internal structure niques that can be used. As previously
of an instrument is tested through factor mentioned, construct validity testing is