Editor’s Note: Ian Sefferman is co-founder and CEO of MobileDevHQ, a company that provides app store optimization and marketing tools. His guest post contains data pulled from the company’s backend and an analysis of how a mobile app’s rating in the App Store and Google Play top charts can be correlated to an app’s rank in search. You can follow him on Twitter, @iseff, or read his blog.

It’s clear that app stores take app ratings into account when ranking an app in search results and top charts. Not only does this help propel deserving apps to the top, but it also helps you sort through all the crap that unfortunately and inevitably clogs app stores.

But, beyond knowing that rating does affect search position and chart rankings, how does rating affect search position?

iOS

Search Rankings

Intuitively, you would expect that the higher an app is rated, the higher it will rank. That’s essentially what our data showed, with one important twist.

In iTunes App Store, the higher positions generally had higher rated apps. We took a random sample of “easy” search terms, “medium” search terms and “competitive” search terms. For the purposes of this post, easy is defined as having 1 to 25 results, medium as having 26 to 100 results and competitive as having more than 101 results. We then averaged the ratings of apps from positions 1 through 10. The twist is that, on average, rating drops significantly after position 8.

Our rational thought process for understanding the top 10 results for any search term is that the first 10 apps will be the highest rated, as well as the most relevant for that keyword. But, as the data shows, the ratings can reach as low as 1.09 for an app ranked tenth for an “easy” search term. That’s a pretty terrible rating paired with a respectable search ranking. Although visibility for an app ranked tenth for easy search term is not nearly as impressive as that for a No. 10-ranked app for competitive keywords, the rating for an app ranked No. 10 for competitive keywords is still, on average, down to a little over 2.

The initial data we pulled for this analysis was taken prior to Apple’s Chomp Update, which is significantly changing how iTunes App Store is ranking apps. That said, our initial analysis shows that average rating has not played a major part in this change. We’ll keep watching for updates.

Top Charts

Even more surprisingly, iOS top charts behave very similarly, if not a little worse. What this means is that the apps in the top charts did not necessarily reach that pinnacle of visibility through ratings alone. We know that download velocity has a lot to do with top charts, but it would seem intuitive that inclusion in Top Charts would, among other things, mean high ratings. The data, however, does not back this up.

Drawing from this, it means rating isn’t everything. It means something — but it certainly seems to mean a lot less than other factors such as download velocity.

Google Play

Search Rankings

We performed the same analysis for Google Play. What we found is that the top 10 search results returned for any difficulty were rated highly; there was no drop like the one seen in the iTunes App Store. We believe this means Google Play weights rating more heavily in search rankings than iTunes App Store does.

From that, we can draw the conclusion that high rating/high quality equals a higher chance of breaking into Google Play’s higher-ranked search echelons. Google Play’s search algorithm seems to take a more meritocratic approach to app discovery and visibility, letting higher quality apps rise to the top.

Top Charts

Yet again, Google Play’s Top Charts calculations appear to value high ratings heavily in top charts. While a high rating may not be sufficient to be in the top charts, it would appear to be necessary.

Conclusion

Those apps fortunate enough to find themselves within the top strata of either search results or top charts are generally rated highly. This trend, however, appears to be more true on Google Play than on the iTunes App Store.