Revenue in two garden centres

Use this diagram to explain that the least squares line for predicting Y from X is different from the least squares line for predicting X from Y.

Firstly click the checkbox Shop B to see the residuals for predicting weekly revenue in Shop B from that in Shop A. Drag the red arrow to make the residuals small.

Now uncheck this checkbox and click Shop A to see the residuals for predicting Shop A's revenue from that in Shop B. These are horizontal lines in the scatterplot. Observe that the residuals are fairly large and drag the line to make them smaller.

Finally, set both checkboxes and drag the line. The two bars representing the two kinds of residual sum of squares show that different lines minimising the two residual sums of squares.

The data are artificial. but are supposed to be weekly sales figures ($000) in two similar garden centres over 100 weeks. Values are correlated due to weather, etc.