“Keep in mind that generally, modifying your ad code is against AdSense program policies. However, we’ve checked with our policy folks and they’ve given our publishers permission to modify the code for use with this specific script for the purposes of A/B testing. Please be aware that the AdSense team isn’t able to provide any support or troubleshooting help for this script or this sort of testing.”
If you read the 15 adsense mistakes, remember that this script is for testing purposes only and is the only one officially allowed. If you love finding new adsense secrets, this adsense tip is truly very useful. By using this script, you can easily determine which ad unit is performing better in that location, switch to that adsense code after testing it and make more money!