In my last post, I discussed the necessity of marketing your app if you want it to be noticed.  Long story short, some apps take off on their own, but not many.  You can do a lot for free (promote on social media channels, your website, submit to review sites, etc.), but you may also consider paying for exposure. There are a zillion options, up to newspaper and television advertising, but you should look at in-app advertising networks first.  They target only users that have the devices you support, and a single click can take your potential users to your app’s download page.

Within advertising networks, you still have a zillion options.  If you plan on putting substantial marketing money behind your app, you should try several to see what nets you the best returns.  You can pay per impression, per click, or per download.  Most ads will be banner ads shown inside another app, around 320×50 on a 480×320 screen, or a size scaled to match on higher-resolution screens.  You generally won’t be able to buy for a specific keyword.  You will often be able to choose between text or image ads.  You might be able to buy full-screen interstitial ads, and you can even buy ads that appear as notifications in the user’s status bar.  Of all those options, the only one I recommend against is the last one – notification ads.  Users HATE them.

I recently ran a quick test on my newest app, Hoofit?, to see what results I could expect from an AdMob campaign.  I had run some small tests a few years ago that came in around $2.00-$2.50 USD per download, which was not reasonable for an app that made about $.03 of advertising revenue per user.  Since then, there has been one major improvement to advertising on Android – it’s now possible to link directly to an app rather than to search results with only that app included, so the downloads have less friction.  I figured my cost per download would be a little lower this time, but I didn’t expect to find a good strategy, just a good story.

I ran two campaigns, one with a text+icon ad, one with a single image banner ad.  Text+icon ads have a minimum bid of $.05*, and image banners have a minimum bid of $.15.  As I result, I expected the text ads to do better, but I was ready to be surprised.  Here are the results:

Text ad:  $10 spent, 38,856 impressions, 201 clicks, 0.52% Click-Through Rate, 3 installs, $3.33 per install

Image Ad: $36.16 spent, 282,405 impressions, 257 clicks, 0.09% Click-Through Rate, 3 installs, $12.05 per install

Look at the difference in click-through rate.  I attribute this to the information contained in the ads.  The text ad’s copy was “Free Walkable Neighborhoods App.”  So it told people what the app was about, and contained the magic word “Free.”  On the other hand, the image ad was just the app name “Hoofit?” with a logo.  In one sense, the CTR really doesn’t matter – I’m paying per click, and AdMob had plenty of inventory it was willing to give me, even for an ad with a terrible CTR.  On the other, with a 0.09% CTR, I suspect a fair percentage of clicks were purely accidental, and that certainly doesn’t help conversion rates.

Overall, I’m disappointed that my best attempt of two cost $3.33 per install.  I imagine I could do better by trying multiple different ad copies as well as multiple different landing pages (changing my app’s description to better catch people’s eyes).  My conversion numbers would also be higher if my app appealed to a larger slice of all app users.

My advice to anyone else setting up a self-serve AdMob campaign:

• Unless you can really wow people with a 320×50 image (perhaps with a gorgeous game screenshot come to mind), stick to the (67% cheaper) text ads rather than images ads.
• Write your ad copy with conversions in mind, not clicks.  Shade your ad copy slightly towards describing what the app does over click-bait words (new, improved).  AdMob will favor high CTR ads over low CTR ads for the same bid, but they also have plenty of inventory available for low-CTR ads at this point.  Try to keep your CTR over, say, .2%, in order to keep down the percent of clicks that are outright mistakes, but don’t worry about it too much after that.  One exception: if you are running a very large campaign ($1000+ per day), you may need to adjust to favor CTR in order to get your desired reach, or you might just up your bid per click a bit.
• Try out different ads and different app descriptions to optimize your yield
• Make sure to try out pay-per-download services like GetJar and compare your results.  In my experience, you can get downloads there for less than $.50 each.  The downside is that the downloads come from outside the Android Market, so they don’t contribute to your ranking within the Market
• Make sure you’ve got a great app before you start spending money to market it

*The minimum bid is $.03 if you don’t target specific countries.  My app only has data for 4 countries, so I had to target them specifically in my campaign