Measures of variability are successfully used in predictive modeling in research areas outside of education. This study examined how standard deviations can be used to address research questions not easily addressed using traditional measures such as group means based on index variables. Student survey data were obtained from the Organisation for…

This investigation reports on the cross-cultural equivalence testing of the Self-Description Questionnaire II (short version; SDQII-S) for Indigenous and non-Indigenous Australian secondary student samples. A variety of statistical analysis techniques were employed to assess the psychometric properties of the SDQII-S for both the Indigenous and…

The stability of Rasch test item difficulty parameters was investigated under varying conditions. Data were taken from a mathematics achievement test administered to over 2,000 Australian students. The experiments included: (1) relative stability of the Rasch, traditional, and z-item difficulty parameters using different sample sizes and designs;…