Like Hi Lo and Box graphs, Westinghouse graphs display multiple Y values for each X value. For the Westinghouse graph, two Y values are needed for each X value. However, the Westinghouse graph partitions the graph into two sub-graphs within the same window: the top one showing the relationship between X and the first set of Y values and the bottom one showing the second set of Y values. The Westinghouse graph is typically used in statistical applications where the top graph displays the mean value and the bottom graph shows the variance of some quantity.