Interpreting gains and losses in conceptual test using Item Response Theory

TL;DR

This paper demonstrates that Item Response Theory can effectively predict and analyze gains and losses in students' conceptual test answers, revealing the non-deterministic nature of responses and providing guidelines for interpretation.

Contribution

It introduces a novel application of IRT to quantify and interpret gains and losses in pre/post conceptual tests, accounting for non-learning-related answer changes.

Findings

IRT predicts gains and losses well on the Force Concept Inventory.

Up to 25% of answer changes are due to non-deterministic factors.

Gains and losses can vary from 0% to 100% without learning.

Abstract

Conceptual tests are widely used by physics instructors to assess students' conceptual understanding and compare teaching methods. It is common to look at students' changes in their answers between a pre-test and a post-test to quantify a transition in student's conceptions. This is often done by looking at the proportion of incorrect answers in the pre-test that changes to correct answers in the post-test -- the gain -- and the proportion of correct answers that changes to incorrect answers -- the loss. By comparing theoretical predictions to experimental data on the Force Concept Inventory, we shown that Item Response Theory (IRT) is able to fairly well predict the observed gains and losses. We then use IRT to quantify the student's changes in a test-retest situation when no learning occurs and show that $i)$ up to 25\% of total answers can change due to the non-deterministic nature of student's answer and that $ii)$ gains and losses can go from 0\% to 100\%. Still using IRT, we highlight the conditions that must satisfy a test in order to minimize gains and losses when no learning occurs. Finally, recommandations on the interpretation of such pre/post-test progression with respect to the initial level of students are proposed.