Google's Internet marketing platform AdWords places ads within search engine results: most people now understand this concept. Generally, people will not notice if the ads change on a page-to-page basis. For example, if I was one of the very low number (by percentage) of searchers that went beyond the first page of results, would the ads remain the same or change? The answer is in the number of advertisers bidding on a particular term. There can be as many as 11 (sometime 12) sponsored results within a Google search result page: 3 on top of the results - in rare cases 4- and up to 8 on the side of the page. So if there are dozens of advertisers bidding on the term, it will take quite a few pages to sift through before you found a duplicate on the side. ***Note that if an ad is in the top three, it will stay there on subsequent pages of the results.
An interesting question was posed the other day at Search Engine Watch Forums, asking if a searcher goes beyond the first page of results and "sees" a sponsored listing again, would that be credited as an additional "impression" in its statistics? He adds that this could make a difference in the performance of the ad, since total impressions versus click-through total is measured as "Click-Through-Rate," and CTR is one of the factors used in determining ad position. The answer, according to paid search expert and moderator Frank Watson, aka Aussiewebmaster, is that yes they do count as multiple impressions. He also ads with justified urgency that
The famous back button contributes to the high numbers Google - and other engines - are getting!!!SEW's "AdWords Rep" joined the discussion and confirmed that the ads receive multiple impressions on their stats, but pointed out that advertisers are not charged by impression, rather by actual clicks. He failed to address the important point of a negative effect on CTR. I personally feel that Google should not count these as multiple impressions, unless they somehow discount them, especially in the case of the top three advertisers, who's CTR can be even more important for high-costing terms.
Join the discussion and give your thoughts at Search Engine Watch Forums.