In a study comparing productivity in two factories, one in an urban setting and one in a rural setting, a city wide strike may affect life for subjects in the first group but not those in the second. This is an example of
A)selection interacting with history
B)attrition
C)a simple selection effect
D)selection interacting with instrumentation

Question

Quizplus · Accepted Answer

The city-wide strike is a historical event that affects only the urban group, creating a confounding variable that interacts with the selection of the urban setting, thus affecting the study's internal validity.

In a Study Comparing Productivity in Two Factories, One in an Urban