IB Maths AA SL 4.10 - Regression Lines

This IB Maths AA SL Topic 4.10 – Regression Lines resource develops students’ understanding of the distinction between the regression line of y on x and the regression line of x on y. It begins by reviewing regression as a straight-line model used to describe relationships between two variables and make predictions within a sensible range. Students learn that the order of the variables matters: a y on x line predicts y from x, while an x on y line predicts x from y.

The lesson develops confidence in finding both regression equations using a GDC, interpreting their gradients and intercepts in context, and selecting the correct line for a given prediction. Students explore why simply rearranging one regression equation does not generally produce the other regression line and compare predictions made using the correct and incorrect models. The resource also examines the reliability of regression predictions, including the effects of weak correlation, extrapolation, non-linear relationships, changing contexts, and using the wrong prediction direction. With clear explanations, worked examples, contextual applications, exam checklists, and detailed calculator instructions for the TI-Nspire CX/CX II and Casio fx-CG50, this resource helps SL students build strong regression and statistical modelling skills in line with IB Mathematics AA expectations.