A researcher is carrying out a study of the effects of teaching different approaches to argumentation on writing persuasive essays. He pretests the participants by having them write three persuasive essays prior to the study, and three essays after the study. He has two individuals grade all the essays. The two individuals were given no training prior to the study. The essays from the students in the study actually looked worse rather than better after the study. Based on the information presented above, what threat to internal validity could explain the contradictory finding?
A) Selection
B) Maturation effect
C) Instrumentation
D) History effect

Question

Quizplus · Accepted Answer

The lack of training for the graders could lead to inconsistent grading standards, which is an instrumentation threat to internal validity.

A Researcher Is Carrying Out a Study of the Effects