After reading this chapter, you should be able to:

1. Describe two criteria that make variables suitable for scientific investigation.
2. Delineate the need for constructs and operational definitions in research.
3. Distinguish between continuous and discrete variables, as well as between quantitative and qualitative variables.
4. State the four scales of measurement, and provide an example for each.
5. Describe the following types of reliability: test-retest reliability, internal consistency, and interrater reliability.
6. Describe the following types of validity: face validity, construct validity, criterionrelated validity, and content validity.
7. Define and give an example of intervention fidelity.
8. Identify the concerns of participant reactivity, experimenter bias, and sensitivity and range effects for selecting a measurement procedure.
9. Explain why the failure to replicate a result is not sufficient evidence for fraud.