Psychometric theory addresses the measurement of psychological constructs. Measurement ties theoretical concepts to empirical indicators, where such concepts represent underlying variables [Page 1111]that are inferred from observable responses. Measurement quality is high when there is a large degree of correspondence between observable indicators and the unobservable concept they represent. The greater the correspondence, the more meaningful the correlations among the underlying concepts will be.

In health communication, researchers might ask smokers how much they enjoy smoking and the degree to which consuming tobacco products is dangerous. If questionnaire items are objective and easy to understand, then researchers are likely to find a negative correlation between enjoyment and perceived risk of smoking. By contrast, measurement quality is low when there is a small degree of correspondence between ...