For more than half a century, publishers (TV, radio, print publications, etc.) have used "impressions" as the primary metric by which the cost for advertising has been measured. In an era of mass media, in which it was practically impossible to measure the number of true viewers, listeners, and readers, it was as close as they could get to measuring the (potential) impact of an advertiser's message. But in 2016, it is my belief that these publishers continue to use impressions, not because it is the best they can do to measure the effectiveness of their platforms, but because it is the most sure way for them to make money. Now I don't begrudge these businesses for making a profit. After all, that's presumably why they exist. But the biggest reason so many publishers are still charging for impressions is because advertisers, many of whom simply just don't know any better, are continuing to pay for impressions, even though there are better, more cost-effective ways.
I'm amazed that there are still marketers out there that don't have a screen full of metrics in front of them virtually every day. As recently as 10 years ago I would have had some compassion for this oversight, but today, it occurs to me that there can only be a handful of reasons why any marketer doesn't stay glued to their analytics. If you are one of the holdout marketers that is not measuring your effectiveness, it is probably for one of the following reasons:
In the good old days of mass-media marketing, agencies and marketing executives were loath to provide quantifiable evidence of the effectiveness of their marketing efforts. But as Internet marketing took off, companies began to realize that they could use online metrics to (at least partially) measure the success of their marketing efforts and it could be as simple as counting the number of information request forms or online purchases submitted from their website each month. Interestingly though, content marketing—while the most powerful strategy for growing small to medium-sized business today—has actually complicated the process of quantifying success.