Scale Dimensionality (Sessions 7 and 8)

Validity-
How accurately does the scale measure the concept it says it measures?
How much systematic error do I have?

Face Validity
1) on the face of it, does it seem to measure what I say it does.
2) assessed by asking individuals in the field to review items.

Content Validity
1) A scale or measure has content validity when all aspects of the concept have been covered. These are frequently referred to as domains.

Criterion-Related Validity
1) researcher compares scores on the measure under development with some external criterion known to or believed to measure the same concept.
2) researcher creating measure determines criterion. The closer the criterion is to the measure in concept the better.
3) concurrent validity: criterion and present simultanously with  the measure you are developing.
Predictive validity: criterion is in future.
4) construct validity: has the unobserved construct underlying the measure being developed been measured accurately
5) one traditional way of assessing construct validity is to look at series of studies using the measure being developed. How well do findings reflect the theory underlying the measure.
6) Statement of validity on the way a measure relates to other variables within a system of theoretical relationships.

Confirmatory Factor Analysis
1) another way is through confirmatory factor analysis in which one hypothesizes that the construct is made up of several domains and particular items belong to one particular domain.
2) one can then test the hypotheses and the model statictically