I chatted with George at Straply at length at a startup event. He says they track the actual Apple App Store and Google Play searches and they have 2MM searched

I chatted with George at Straply at length at a startup event. He says they track the actual Apple App Store and Google Play searches and they have 2MM searched phrases in their database. The phrases that people are actually searching for with the misspelled words and all. As far as ranking keywords I'm pretty sure it's on the actual number of times phrases are really searched. No guess work. That being said, you might want to reach out to George. Seemed like a pretty good dude.