I am trying to visualise a data set with three independent variables (two categories and a time scale) and one dependent variable (count). What would be the best way to show this data?
One way that I've found useful is to display (quasi) continuous variables (count, time) on an x,y scatter plot, then distinguish the categorical variables by shapes and colors. So if one of your categorical variables has 2 levels and the other 3, use squares versus circles for the first and three different colors for the second. How well this works, of course, will depend on your data and what you wish most to visualize.