In order to know how effective a specific Web site or ad placement is, use distinct channels and subchannels within Google. This will allow you to discern what performs best on a specific Web site. Using channels will tell you what sites are making money, what advertisements are making money and what ad position is the most profitable on a specific Web site. Keep in mind that you should run an advertisement for a full week, in order to properly test its effectiveness, different days of the week will vary the Web traffic so comparing one week to another will give the most accurate reflection of how effective a campaign performs.
When testing different advertisement sizes, placement or color schemes, be sure to leave campaigns in place for one week. Different days will often result in Web traffic fluctuations. Comparing Web traffic week to week will give a clear indication of what ad formats perform the best.

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