Utilizing Rasch analysis to establish the psychometric properties of a concept inventory on concepts important for developing proficiency in organic reaction mechanisms

Abstract

Undergraduate organic chemistry has been found to be historically difficult for students and one area where students struggle is organic reaction mechanisms. The difficulties students face with reaction mechanisms has been a source of interest in chemical education research but most studies done have been purely qualitative. An assessment tool that could be used on a large-scale for instructors to gauge the difficulties their students face, would be useful. The aim of this pilot study is to use Rasch analysis to establish the validity and reliability of the concepts important for developing proficiency in organic reaction mechanisms inventory (RMCPI). The test, containing 25 items, was administered to first semester organic chemistry students (N = 44) at a mid-sized university. The data was analyzed using Rasch techniques to explore the dimensionality of the instrument, the difficulty of the items, the item fit, and the reliability. The results indicate that the instrument is unidimensional and most of the items fit well to the dichotomous Rasch model. The test was found to be difficult and this will be explored further by increasing the sample size, administering the test to students from other universities and increasing the number of items on the inventory.

Keywords

• concept inventories
• organic reaction mechanisms
• rasch analysis