Do Impressions Matter in Search Marketing?

For clients new to search marketing, I have often explained the concept to them as "only paying for results."  In effect, the beauty and sales proposition of search marketing has always been that you are only paying for clicks, and impressions are essentially free.  I anticipate for many SEM professionals, this has also led to a somewhat derogatory discussion of impressions.  I wouldn't be surprised if some clients now have the view that impressions don't really matter online.  Or at least that they matter less.  But is this really true?  Where does the lowly impression fit with all this recent discussion about clicks, click-through-rates, conversions, and now with even more measurable innovations like pay-per-call? 

For some of our clients, I would argue that impressions are more important than ever.  Take two recent data points.  The first is that search use by the overall Internet population is growing.  The second is that often people cannot recognize the difference between sponsored search results and organic search results.  The conclusion I would put forward from this is that people are paying attention to sponsored search results while they are avoiding nearly every other kind of online (and offline) advertising messages.  And this group is growing.  Of course, a user will probably only click one or two search results (organic or sponsored).  But unlike other forms of online advertising, they read and often absorbed the messages of those sponsored listings they never clicked on. 

That was a "meaningful impression," even though you didn't pay for it, and you couldn't measure it.  It even have lead to a future action.  Almost every form of offline advertising (aside from direct marketing) is based on blind faith that this meaningful impression exists. Why is it so counterintuitive to imagine that it would exist for search marketing too?  The problem is, in the minutely measurable world of SEM, the meaningful impression is something that we cannot yet measure.  And as a result, we leave it out of our reporting to clients.  But it does exist, and it is our responsibility to start telling clients about it.  Impressions do matter.