Even with more data points, I'm not convinced that App Store ranking is a good independent variable. At best, this seems like a very poor proxy for ad store imp

Even with more data points, I'm not convinced that App Store ranking is a good independent variable. At best, this seems like a very poor proxy for ad store impressions or downloads. However, I would be very, very surprised if the relationship between those legit metrics and app store ranking were anywhere near linear when you're comparing the top 5 or so to the rest of the top 25.