Aug. 12, 2010 at 9:59am with 33 notes View comments

Android Market Ranking Algorithm: The New Black Box

While you won’t find much information on this, savvy Android developers are aware of one of the big secrets in mobile; The Android Market is ranked via a Black Box algorithm. Most people just assume it is sales/downloads. I’ve even seen articles written where there was an assumption of sales based on who was ranked #1. That’s not the case.

In my time working with the Android Market (which would be about a year and a half), I’ve watched two different apps, one paid and one free, fluctuate in rankings. I’ve also watched how other apps across all categories perform over time. Early on I realized there was no standard order like on the iPhone app store. With iTunes, rank is purely download based. Sell the most, you’re the top. It’s simple, it works, and people want to sort products by bestselling (e.g. BestBuy.com, New York Times Bestseller list, etc). But Google had other ideas…

It looks to me as though Google brought their search ranking algorithm to the Android market. Having an SEO background, I’m probably more attuned to this and the accompanying frustration. Instead of simply ranking by sales, Google decided they needed to be different where they should not. I believe Google should have ranked by sales first, and then, if clearly it wasn’t working they could have approached it a different way.

The top apps in a category are not necessarily the top downloaded in that category. I like to use the example of paid apps since the download numbers are still small enough that patterns are obvious, but a year ago with free apps the same pattern was apparent (you just can’t see it now since the top apps are all above the max threshold of 250K). Today, you can take a look in the paid “Tools” category and see that the #3 ranked app is in the 10-50K downloads, and the the #4 is in the 50-250K downloads. You can look at the travel section and see the top ranked app with 1-5K downloads, and the #3 ranked app with 10-50K downloads. When MySpace claimed back in March they were the most popular (i.e. most downloaded) social networking app on the Android, everyone scratched their head.

I knew the answer. The answer was that no one knows who had #1 most popular social networking app. Myspace was simply the #1 ranked app, which means nothing. Facebook could fully have more users and more downloads, but since the rankings aren’t based on downloads no one would know.

What we’re left with is some anecdotal evidence, rumor, and speculation as to how the ranking works. My best guess is that the following factors are included:

-Ratings

-# of Ratings

-Install/Uninstall Rate

-Anonymous usage stats

-Total Downloads

-“Velocity”

-Black Magic

All of this was gathered at Android conferences like Google I/O and keeping my ears open in the Android development community. I saw a tweet once from what I believe was a Google Labs session where the audience was told that anonymous usage statistics (i.e. length an app is usage and frequency) is a factor. How does that even make any sense? I can run a GPS app for 8 hours, but only spend 10 seconds with a Tip Calculator app. Both are listed in the same category. One would benefit and the other would suffer.

What can a developer do? Do we need an SEO-like panel to have people in the industry gauge ranking factors for the Android market? Do we simply add this to the many “wants” for the Android Market? Or do we look for the carriers to bring order with their own Android app stores? Ultimately there need to be some changes with the Android Market to support developers, and default sorting by sales/downloads is one of them.