Split Testing Ads & Margin Of Error

Is your winning add really a winner? If you’ve got two ads that have different click-through rates right now, how sure can you be that those ads will perform differently in the long run? Enter your clicks and CTR’s for each ad and SplitTester will tell how how likely they are to have different long-term results.

http://www.splittester.com/

You can also use this formula below to determine margin of error. Where p=CTR (decimal form) and n=impressions.

 

margin of error formulaFor example, if you have two ads; Ad 1 has 4500 impressions with a CTR of 1.25% and Ad 2 has a CTR of 2.5 with 6000 impressions. The margin of error for Ad 1 is +/- 0.32% .W e are 99% confident the CTR for this ad will be in the range of 0.93% and 1.57% (+/- 1.25%).  The margin of error for Ad 2 is +/- 0.4%. We are 99% confident the CTR for this ad will be in the range of 2.1% and 2.9% (+/- 2.5%). It is safe to say Ad 2 will always have a higher CTR than Ad 1.

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