Page 562 - Encyclopedia of Nursing Research

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Content validity determines whether
Validity the items sampled for inclusion adequately
represent the domain of content addressed
by the instrument. The assessment of con-
Validity refers to the accuracy of responses tent validity spans the development and
on self-report, norm-referenced measures of testing phases of instrumentation and super-
attitudes and behavior. Validity arises from sedes formal reliability testing. Examination
classical measurement theory, which holds of the content focuses on linking the item
that any score obtained from an instru- to the purposes or objective of the instru-
ment will be a composite of the individu- ment, assessing the relevance of each item,
al’s true pattern and error variability. The and determining if the item pool adequately
error is made up of random and systematic represents the content. This process is typ-
components. Maximizing the instrument’s ically done by a panel of experts, which
reliability helps to reduce the random error may include professional experts or mem-
associated with the scores (see Reliability), bers of the target population. Lynn (1986)
although the validity of the instrument helps has provided an excellent overview of the
to minimize systematic error. Reliability is judgment- quantification process of having
necessary but not a sufficient requirement judges assert that each item and the scale
for validity. itself is content-valid. The results of the pro-
Validity and theoretical specification cess produce a content validity index, which
are inseparable, and the conceptual clari- is the most widely used single measure for
fication (see Instrumentation) performed in supporting content validity. Content valid-
instrument development is the foundation ity should not be confused with the term
for accurate measurement of the concept. face validity, which is an unscientific way of
Broadly stated, validity estimates how well saying the instrument looks as if it measures
the instrument measures what it purports to what it says it measures. Although content
measure. Underlying all assessment of valid- validity is often considered a minor compo-
ity is the relationship of the data to the con- nent for instrument validation, researchers
cept of interest. This affects the instrument’s have repeatedly found that precise attention
ability to differentiate between groups, pre- to this early step has dramatic implications
dict intervention effects, and describe the for further testing.
characteristics of the target group. Criterion validity is the extent to which
Literature usually describes three forms an instrument may be used to measure an
of validity: content, criterion, and construct. individual’s present or future standing on
These forms vary in their value to nursing a concept through comparison of responses
measurement, and unlike reliability, singu- to an established standard. Examination of
lar procedures are not established that lead to the individual’s current standing is usually
one coefficient that gives evidence of instru- expressed as concurrent criterion valid-
ment validity. Instead, validity assessment ity, although predictive criterion validity
is a creative process of building evidence to refers to the individual’s future standing. It
support the accuracy of measurement. is important to note that rarely can another