Chapter 3: Three claims, four validities

In this chapter we'll cover the following learning objectives:

1. Identify variables and distinguish a variable from its levels (or values).

2. Discriminate between measured and manipulated variables.

3. Describe a variable both as a conceptual variable and as an operational definition.

4. Indicate how many variables frequency, association, and causal claims typically involve.

5. Describe positive, negative, and zero associations.

6. Identify verbs that signal causal claims versus association claims.

7. Apply the three criteria used to evaluate a causal claim: covariance, temporal precedence, and internal validity.

8. Identify examples in which writers' and researchers' claims are not justified by the studies they are describing.

9. Appreciate that few studies can achieve all four kinds of validity at once, so researchers must prioritize some validities over others.

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