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…

Most existing research indicates that working students perform more poorly than do full-time students on standardized achievement tests. However, we know there are wide international variations in this gap. This article shows that national and international contexts help to explain the gap in the academic performance between working and nonworking…