Campbell & Stanley's threats to internal validity


Discuss Campbell & Stanley's threats to validity. To help students,
1. Make an overhead of page 273 (both Table 9-2 and Figure 9-5).
2. Realize that students will tend to have trouble understanding regression (therefore, you may want to use demonstration 1 or 2.).
3. Realize that students will tend to confuse testing and instrumentation.
4. Realize that students will tend to confuse maturation and history.
5. Realize that the discussion of these threats sets up three very important concepts:
a. correlation does not prove causality.
b. the simple experiment really is a remarkably easy way to establish internal validity.
c. The key to experimental and quasi-experimental designs is to show that these threats are unlikely explanations for the obtained results.

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