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, and 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, criterion-related validity, and content validity.

7 Identify the concerns of participant reactivity, experimenter bias, and sensitivity and range effects for selecting a measurement procedure.

8 Explain why the failure to replicate a result is not sufficient evidence for fraud.

9 Enter data into SPSS by placing each group in a separate column and each group in a single row (coding is required).