Testing Different Adsense Ad Formats at Same Location by Displaying Them Randomly

• Create Two Custom Adsense Channels. Name them accordingly as per your needs. In this case its 728 x 90 and 468 x 60 but you can use any other formats too like 336 x 280 and 300 x 250 and so on.
• Now you need to setup the ad formats similarly. What i meant is, when the final code is obtained only google_ad_channel, google_ad_width, google_ad_height and google_ad_format should only be the variables. Every thing else like Title, Color, Font etc should be same, now that would be more logical to test between the two formats simultaneously. However, its not mandatory that you should only use similar looks for the two formats.
• Now we are going to play with the java script code. Here we are mixing up the to different adsense codes so that each of them will be displayed 50% of the time. And it total both counts to 100% in overall. Here is a code shown as example.

  <script type="text/javascript">
   var google_ads = Math.random();
      if (google_ads < .5){
        google_ad_channel = "468x60Channel";google_ad_width = 468;
        google_ad_height = 60;google_ad_format = "468x60_as";
      } else {
        google_ad_channel = "728x90Channel";google_ad_width = 728;
        google_ad_height = 90;google_ad_format = "728x90_as";
      }
        google_ad_client = "pub-xxx";google_ad_type = "text_image";
        google_color_border = "FFFFFF";google_color_bg = "FFFFFF";
        google_color_link = "0000FF";google_color_text = "000000";
        google_color_url = "0000FF";
  </script>
  <script type="text/javascript"
        src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
  </script>

• Check out the performance of the two ad formats for a week or two to determine which of the adsense format gives you the best CTR, eCPM. Some times the 336 x 250 ad unit give you more clicks than the 300 x 280. It depends.

The next time after this experiment you can try two formats with a different color format, different font (change fonts in adsense ads), font size etc.