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5 Sources of Inaccuracy in AdWords Testing & Tracking (And how to eliminate them)

Google Adwords

“Test, test test!”

It’s the unglamorous advice that no one wants to hear–except the few people who actually do it and seize the fistfuls of cash that lazier advertisers are leaving on the table. Let there be no doubt–sustained, serious testing is what separates the men from the boys in Google AdWords. It is what allows you to move beyond the theories and promises of e-books and instructional PDFs and see the reality of your actual, unique PPC campaigns. It is what guides you in making profitable tweaks and changes. But be careful! If you make any of these 5 mistakes, your test results could be inaccurate and lead you on a wild goose chase away from profitability!

  1. Statistically insignificant split tests
    Every AdWords marketer should be familiar with the concept of statistical significance. That is, if you are running 2 ads against each other in order to determine the higher-performing ad, you cannot make your decision after a day or two. Rather, you need to give each ad enough time to run so that when the results emerge, you can confidently say the ad with better stats is truly the better one. Without allowing this time to pass, how can you be sure the apparent “winning” ad is not just a fluke that benefitted from a random spike in clicks? If this sounds puzzling or time-consuming, don’t worry, it’s not.

The free calculator at can determine in seconds whether you have enough campaign history to prove ad A really is outperforming ad B. Use this before making any split testing decisions on your Google ads!

  • Not tracking profit per impression
    RocketClicks co-founder Glenn Livingston was quite possibly the first marketer to realize that profit per impression is the most important AdWords-related metric–not click-thru rate (CTR) or conversion rate, but which ad put the most money in your pocket each time it was displayed. As he notes in his PDF report on the subject [emphasis added]:


“Google has everybody focused on CTR and conversion. But CTR + conversion individually don’t give you the right information to make your critical split testing decision. You might be surprised to note that Google isn’t really pricing their traffic according to CTR, even though that’s how you pay for it. All they have to sell you is space (impressions), so they’re doing the math behind the scenes to figure out how much money they make per impression.”

It should go without saying that this is the number that counts. Fortunately, there’s a free web-based calculator that will let you determine profit per impression without putting together any spreadsheets or formulas. Use it!

  • Prioritizing CTR above conversion rate
    An even deadlier testing sin than not tracking profit per impression is prioritizing CTR above conversion rate in your tests. This is a serious error because as a PPC marketer you really need to be tracking dollars, not percentages. A high CTR in and of itself does not necessarily mean you are making money. In fact, it could mean you are losing money–after all, a high CTR only proves that lots of people are clicking your ad. If they are also buying your product, this is a good thing. But if they are only clicking your Google ad and leaving, your high CTR represents nothing but wasted money.
  • Mixing content network traffic with Google traffic

    Show my ads on...

    If you want to advertise on Google search results pages as well as the content network (the vast array of blogs and websites running targeted Google ads), you should maintain separate campaigns for this. The reason is that clicks from search engine queries and clicks from website ads are different sources of traffic. People are in a different frame of mind and a different place in the buying process depending on which of these ads they click and arrive at your website from. Therefore, grouping them both into one campaign and showing them identical ads serves only to distort your statistics and make it harder to determine which ads are truly making you the most money. Remedy this by going into your campaign settings and making sure only Google search is checked.

    (Note that this is not to say you should ignore the content network. Far from it! We are only advising that you maintain separate campaigns for PPC and content network so that you can accurately measure the results of each of these different traffic sources, rather than muddying the waters by combining them.)

  • Letting Google “optimize” your ad rotation

    Optimize: Show better performing ads more often

    In all their benevolent wisdom, Google will, by default, monitor which of your ad(s) get the highest CTR and display those most often. At first glance this sounds helpful–who wouldn’t want to put their best foot forward and show their highest performing ad as much as possible? But this is actually not your goal. As an AdWords marketer doing serious testing, your goal is to continuously beat your winning ad, thereby pushing your CTR, conversion rates and profit per impression ever higher on an ongoing basis. The only way to achieve this is to give all your ads the same amount of exposure and let the best one win. Luckily, this is not at all difficult. Simply visit your campaign settings and check “Rotate: show ads more evenly” instead of “Optimize.”


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