After reading this chapter, you should be able to

4.1 Describe two criteria that make variables suitable for scientific investigation.

4.2 Delineate the need for constructs and operational definitions in research.

4.3 Distinguish between continuous and discrete variables and between quantitative and qualitative variables.

4.4 State the four scales of measurement and identify examples for each.

4.5 Describe and utilize test-retest reliability, internal consistency, and interrater reliability.

4.6 Describe and utilize face validity, construct validity, criterion-related validity, and content validity.

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

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