How do I show 'selection' with data from two raster layers

[GaiusWilson]

I have a raster layer with human population. I also have raster layers of slope and elevation. How do I show that the human population (or the cells that have higher human population) are selecting for lower slopes and lower elevation? I have reclassified all three layers into the categories I need.

[DanPatterson_Retired]

Combine—Help | ArcGIS Desktop 

will yield a raster with the unique combinations as their classification scheme

[GaiusWilson]

Thank you Dan for your reply. I am sorry I did not see your reply till now. I just tried it, and yes, I can see that the two raster layers combine. Now I am trying to work out how to interpret or convert the output to make sense in terms of a graph or percentage? Thanks for your help in advance. 

[DanPatterson_Retired]

You have a categorical classification scheme, so a bar graph would make sense.  As for percentages/ratio, you could express cell counts divided by the total number of cells (x 100) ie class 3 (high population-low slope-low elevation) represented 40% of the total area.  On that note, your population would best be served if it was reclassed as categories rather than absolute values, similarly to slope and elevation.  It is not the absolute values but the categorical classes that should be run through Combine, otherwise your classes are less meaningful.

[GaiusWilson]

Thank you Dan, yes I have already reclassified population into 5 classes, slope in 4 classes, and elevation into 7 classes. Thank you very much for your advice. I will try this.