Hello
I always say that continuously testing is the key to maximizing AdSense earnings.
Today I want to emphasize this once more with an example from my recent tests.
The last 2 month my AdSense earnings dropped about 1/3 for no apparent reason.
The traffic is nearly the same and I run forum(s) so there is fresh content daily.
I’d like to think that April and Mai are month with low advertising spendings
(in direct sold advertising it is) but anyways AdSense is a long term business and
a few draw backs are not unusual.
I took this “opportunity” and started testing again to see if I can get the numbers
back up by running a few Split Tests.
But what is a split test?
Wikipedia says:
A/B testing, split testing or bucket testing is a method of marketing
testing by which a baseline control sample is compared to a variety of single-variable
test samples in order to improve response rates. A classic direct mail tactic, this
method has been recently adopted within the interactive space to test tactics such
as banner ads, emails and landing pages.
In other words you run different versions of your Ads and divide the flow of visitors
equally between the different versions:
This way you know after a while which version works best for your website and then
by only serving the better version you increased your revenue.
The best way to run a split test is to install an Ad Server. I wrote www.adsenseexperts.com/advanced-adsense-publishers/set-dfp-small-business-serving-ads-sites-t77.html, the free Ad Server from Google.
So if you don’t use an Ad Server yet you might want to start right now.
My recent split tests:
I serve a medium rectangle inside the first post of each thread on my medical forum.
Currently the Ad is set to serve Image&Text Ads.
In general the more competition there is for an ad unit the higher your CPC will be.
However not always does a higher CPC results in higher earnings!
For about 2 years now I never thought it might be possible that images or text only
ads would earn me more then image&text. But like I said, I took the “opportunity”
and started testing. I took one of my sub forums as testing ground and run the test for 2 weeks.
Example from my recent split tests:
Each Ad Unit got around 40k Impressions
Image & Text: CTR ~0,9 | CPC ~34 Cent | RPM ~2,9 EURO
Text only: CTR ~0,3 | CPC ~17 Cent | RPM ~0,44 EURO
Image only: CTR ~1,0 | CPC ~31 Cent | RPM ~3,2 EURO
What does this tell me? (not you! Test it for yourself)
a) Never ever serve text only ads 
b) If I switch to Image only Ads I earn 30 Cents more per 1000 Impressions
c) Even though that the CPC for ‘Image only’ is lower then ‘Image & Text’ Ads, my visitors seem to click Image Ads more often which results in a higher RPM
d) I will expand the test to see if this is a phenomenon in my sub forum or if it works the same way for different topics
e) I made a note to myself to run this test again in about 6-8 month after I switched to image only Ads
Do you see the potential of split tests now?
With investing 5 minutes to set up the split test I increased my monthly earnings about 150 Euro.
And this is just one of the many things you can and should test with AdSense.
For more ideas about what you should also test read this: www.adsenseexperts.com/advanced-adsense-publishers/8-things-test-optimizing-adsense-t194.html
What tests are you currently running?
Any interesting findings you might want to share?