Scatterplot

The relationship between two variables can be visually represented in a scatterplot.

Create data points by clicking anywhere on the graph. As you move your cursor over the workspace the x- and y-coordinates are displayed. When you have two or more points on the graph, a red line appears. This is the regression line, the best straight-line approximation to the collection of points, in the sense that of all straight lines, the regression line minimizes the sum of the squared vertical distances from the points to the line. Its equation is given, along with n, the total number of points, and r, the correlation coefficient, a measure of the linear association between the x-variable and the y-variable.

The default setting for the graph window is -10 to 10 for both variables. To change these settings, enter your own maximum and minimum values and press Apply.

You can edit (move) a data point simply by dragging it with the mouse while holding down the Shift key. To delete a data point, click on it while holding down the Ctrl key.