Select Discrete by Discrete from the Graphs - Graphs of Input Data - 2D/3D Histogram by menu to create a bivariate histogram when you have highlighted a discrete variable in the spreadsheet and you want to plot another discrete variable on the second axis. After you have selected the second variable, the Select Codes dialog is displayed in which you will designate the codes for each variable. Click the OK button to accept all of the codes for both variables.