Some of you may already know, that I am currently experimenting with different "myths" about the all known and very popular question: "Should I go for maximum impressions or better for a maximum CTR?

The main reason which is responsible for these two values are the refreshing time of your ads.

There are many factors involved in these thinkings like when is the ad displayed and mainly if the users "has time" to recognize it. I may write a dedicated article for that subject in the future, but this time I wanna talk about the "CTR vs Impressions" question.

As we all now, the CTR (Click Trough Ratio) does tell you how many percent of your impressions get clicked.

You can read all over the web about how important it is to not waste impressions and go for a higher CTR because it is the only way to get higher paying ads displayed (higher CPC - Cost Per Click)

Thinking about it logically, your ad space inside your game/app is a product and does (or should) work exactly like an advertisement wall you can see beside a street.

For streets it is true, that as more people drive by the ad per day, as more it costs to put your ad there. Take the Times Square in New York for example. If you want to put your ad there, you'll have to pay loads of money for it because so much people will see it and may get attracted by your product. Unfortunately you will not be able to track the overall return of this advertisement, because people cannot click the Times Square Ads .. except Spider Man - honestly, I think Spider Man was paid by Coke to permantly click the Pepsi Ads, so Pepsi was banned because of Click Fraud .. xD

Anyway - as an app developer you get paid by clicks and not by impressions. That lead us to the question what makes your ad space more expensive .. showing your ad very often or provide a good CTR.

From the publisher view, a high CTR would mean, that you are presenting the ads very well and many users are attracted by it - as long as they don't think you make some sort of click fraud with them.

So as you might think (and because advertisers do some sort of bidding for their ads) if you manage to get a natural higher CTR you will get also a higher CPC, so you get more money for each click.

That's also what ad networks will tell you and what your logic will tell you. But the truth is: We don't know it and we cannot control it.

So I started a little experiment where I just raised the Refreshment Time of my ad space to 10 minutes. Which is very long, so users will see an ad for a very long time and hopefully they will recognize it at a moment where they have time or are more likely to read it. If they find it interesting enough they will click on it to get more information.

I had this experiment now running for around 1 week and found out several facts:

My Impressions dropped from ~120.000 to ~35.000 which is around a quarter. So the Impressions quartered - that's normal because the refreshing time before was 2 minutes, so the refreshing is now 5 times less.

Beside that the CTR is climbing up to over 6% - before it was at a rate of around 3%. So it doubled which is not the best thing because mathematically it should have multiplied by 4.
But I have to say, that the CTR is still climbing up by 0.4% every day, so let's wait and see where it ends.

But the real interesting factor is the overal CPC. Normally you do not get the CPC from your ad network, but you can easily calculate it by yourself by dividing the revenue by the clicks.

These CPC was at around 0.027 before and (because I do this experiment with admob) there were also adsense ads involved, which normally gives a slightly lower CPC.

Currently the CPC has not changed very much .. it ranges at around 0.030-0.035 which is mainly because I do not get backfilled with adsense ads any more I get completely filled by admob ads.

The overall revenue so far has dropped by a small amount so as long as the CPC is not getting better a refresh time of 10 minutes seems to be too long. I will watch it a little bit longer and after that I can talk about real facts - there are only some options available:

1. The CPC stays as it is and will not raise: Well than admob does not care for your CTR and it is proofed, that for admob it is better to get a higher impression reate instead of going for a better CTR. Maybe admob does not take the quality of your ad space into account.

If that is true you may consider switching to another ad network which respects your high quality ad space better.

2. The CPC goes up - if that happens, it is proofed that you really should go for a better CTR because that would mean to raise the value of your ad space.

There are many different ad networks out there and some will fit better for high impressions and some will fit better with high CTR (I guess).

So my experiment will gather facts about admob in the first place and may be continued with other networks in the future.
MoPub seems to be a good candidate for future investigations - so stay tuned!