In an experiment, teachers' judgments are used to measure the amount of misbehavior among students. The teachers are more likely to judge a given behavior as misbehavior at the posttest than they are at the pretest. This example most clearly illustrates which threat to the internal validity of the experiment
A)testing
B)instrumentation
C)history
D)statistical regression

Question

Quizplus · Accepted Answer

Instrumentation refers to changes in the measurement instrument itself (in this case, the teachers' judgments) that might affect the outcomes. If teachers are more likely to judge behaviors as misbehavior at the posttest, it suggests that the 'instrument' used for measurement (teachers' judgments) has changed over time, affecting the validity of the experiment.

In an Experiment, Teachers' Judgments Are Used to Measure the Amount