Could you interpret these screen resolutions from Google Analytics? After choosing Macintosh in my Google Analytics stats and then choosing Screen Resolution as the secondary dimension, I get these numbers:



Which one of these are 15" Macbook Pro, 13" Macbook Pro, etc. 

I'd like to know if the Retina screens are reported in their actual resolution. I don't see any stats for 2560x1600 and 2880x1800. Does this mean that these Retina screens are reported as 1280x800 and 1440x900 respectively?
1440x900 is the native resolution for 15'' non Macbook Pros, and the given  (best/default) resolution for 15'' rMBP with the pixel doubling effect taken into account, as it is. The analytics don't distinguish between the two, so the most you can infer from the data is that the most common model is a 15'' Macbook Pro.