The construction of a scale to measure mathematical ability in psychology students: an application of the Rash model

The purpose of the present study was to develop a scale to measure the math ability that psychology students need to enrol introductory statistics courses inside their degree program. The Rasch model was applied to construct the instrument. The principal component analysis (PCA) of the residual showed a one-dimensional construct; the fit statistics revealed a good fit of each item to the model. The item difficulty measures were examined and the area of ability accurately assessed by the items was identified. The validity of the scale was assessed: the measures obtained by the scale correlated with attitude toward statistics and statistics anxiety (concurrent validity), and a relationship with statistics achievement was found (predictive validity).