More about brushing

In the previous page, we used brushing to highlight a cluster of individuals in a scatterplot matrix. Brushing can be used on any linked displays of the same data set.

Temperature and latitude

In an earlier section, we examined the relationship between the maximum January temperature and latitude of a group of cities in the USA. The diagram below shows three linked displays of the data ...


Drag the red arrow at the top of the residual plot downwards. This brushes over the highest residuals (the cities that are unusually hot in relation to their latitudes). Note that the high residuals correspond to the cities on the plot of temperature against latitude that are furthest above the least squares line.

Now release the mouse button and drag upwards the red arrow at the bottom of the residual plot. This brushes over the cities that are unusually cold for their latitudes.