Numerical variable as my 2nd variable

Hello, I want to use a numerical variable as the second variable in my Dot Plot (with Box and Whisker). NZGrapher would automatically split it into four categories, but I just need two categories. Is there a way we may change it? Thanks

You can click on Sample at the top and select the variable you want to use and then pick the 2 you want by typing in the number to sample.