By the end of this chapter, you will be able to do the following:

6.1 Argue why you should care about measurement.

6.2 Defend the benefits of sound measurement.

6.3 Create different measurement scales, including nominal, ordinal, interval, and ratio scales.

6.4 Construct a new measure by determining a measure’s purpose, defining the attribute, developing a measure plan, writing the measure’s items, conducting a pilot study and item analysis, planning a distractor analysis, selecting the items, and establishing appropriate norms.

6.5 Evaluate and interpret the meaning of the reliability of your new measure using different estimation methods, including test-retest reliability, parallel forms, internal consistency, interrater reliability, and computing the standard error of measurement.

6.6 Gather validity evidence about your new measure, including content-related evidence, criterion-related evidence (i.e., predictive and concurrent), and construct-related evidence (i.e., convergent and divergent), and improve the estimation of validity coefficients by understanding the effects of range restriction.

6.7 Improve measures by enhancing construct validity, clarifying distinctions between reflective and formative measures, and minimizing psychometric deficiency and contamination.

6.8 Set up a five-step protocol to improve the accuracy of estimated relations between variables based on good measures.