If you have a website and you use adsense, its a good idea to carry out some simple tests to see which style/colour/size/position of advert will give you the best Click Through Rate (CTR). Its a pretty simple process, and could see your earnings improve dramatically.
Split testing (or A/B testing) is the name given to a test where one variable is altered in a range of samples, and results monitored to see which sample is the most successful. I have recently carried out tests on ad sizes, font colours and font sizes, and as a result I’ve seen large increases in CTR from my adsense adverts. Google terms and conditions prevent me from saying exact numbers but it is around a 3% increase in CTR, which over time will add up.
I aim to show you how to both implement the test and set up reports within adsense in order to monitor the results. First, lets start with the implementation. I use WordPress in all my sites, so needed a plugin that could rotate ads of my choosing. After much searching I found an excellent plugin called Ad Injection, which allows me to place the ads where I want them with a number of options such as only show ads on posts of a certain length or age and the ability to choose which pages and posts will have ads. The best thing about this plugin for me is the ability to choose up to 10 different styles of ads and rotate them randomly. This meant I could start my split test.
When split testing, the first thing you should figure out is why you want to test. What is the purpose and what do you hope to achieve by testing? My aim with the split test process was to determine which font, which font colour combination and which font size would give the best CTR for my site.
Once I had installed the plugin, it was time to choose the ad location. For this, I went with Google’s suggestion for ad placement – I assume they have done a major amount of testing to determine the best placement area, and I don’t have sophisticated software to determine eye tracking movements, so I decided to stick with Google’s recommendations initially. This doesn’t necessarily mean I will always stick with them, but I had to start somewhere. This isn’t an exact science, therefore some assumptions have to be made.
I have my sites set up with sidebars on the right (as per the layout on the right of the diagram above), so I started testing the ad unit which is in the main body of the the article right underneath the main navigation bar.
Now I had determined the why, the where and the how.
In order to test different adverts, I first had to create a series of ads, each differing in only one aspect. Although the Ad Injection plugin allows for up to 10 different ad styles to be rotated, I decided to stick with 5.
For my first test, I wanted to know the best colour scheme for my adsense ads. I used the Google standard colour scheme, a blue title bar, black text and green link as per the image below.
I tried 5 colour scheme variations, including making the blue bar match the link colour of my website, making the link bar light grey, and making all three lines of text black. For each variation I created a new advert in adsense, and I named it in the format of
Niche-Ad position & size-Test-No.
This is important as when it comes to finding the results you need to know quickly which advert is which.
For example the series of my 5 ads were named:
So at first glance I can tell the site the ad is used on, the position and size and the purpose.
I then cut and paste the 5 separate ad codes into the plugin and waited for the results to come in. So that’s the implementation phase.
In order to be able to see and assess results quickly I used a great feature built into adsense, whereby you can save reports for viewing later. I set up a report to view the performance of the 5 ads over the previous 30 days.
To set up this report click on the Performance Reports tab, then choose Ad Units from the menu on the left. Then click on “edit selections”. There is an option to choose specific adverts. Add the ones you wish to be included and click on update report.
Your custom report will now be displayed, and you have option to save it. I named my report “TEETH-TEST-TOP300x250″ so I could find it easily later.
So now I had set up the test and the report. All that was left to do was wait for the results. I decided that in order to get the best results I would let it run until each individual ad unit had a minimum of 1000 ‘ad requests’. By choosing a larger number I was trying to minimise the impact of unusual events or click activity on the site.
There is no definite amount of time or number of ad requests to let the test run for, but bear in mind the more ad requests you let a test run for, the truer your results will be. I would suggest that 200-300 is the bare minimum number of ad requests to run a test for to get a true reflection of the anticipated long run CTR.
After approximately 1000 requests of each ad, I saw a variance of about 2.5% between the ads with the highest and lowest CTR.
After testing the font colours, it was time to test the font sizes. I used the ad colours that proved to be most successful for my site (which incidentally were: 1. link text – same colour as links on the site, 2. description – black, 3. URL – light grey), and made three ads of different font sizes; small, medium and large.
I again ran the test for a minimum 1000 requests, and set up another custom report in adsense for quick viewing. In the end, the medium font size gave the best CTR on my site.
The final variable I tested was the font itself. This again has three options; Times, Verdana and Arial. After the 1000 requests of each ad, Arial came out on top.
So after carrying out the three tests, I found the ad unit that gives me the best CTR is Arial, with a medium font size and a colour scheme that is blended into my site. This process has led to an increase in CTR of over 3% for this particular ad unit location.
Isn’t it time you tested for the ad unit design that will perform best on your site?