CPP is the amount of money it costs you to reach 1% of the population in your DMA (designated market area) – or, in media jargon, the cost of buying one "rating point" (also abbreviated GRP for "gross rating points"). So if your DMA is 94,000, and your CPP for a particular radio station is $12, that means it cost you $12 to reach 940 people one time.
(Brief digression: I have to be careful here. My one-time boss, Roy Williams, didn't believe in looking at CPP because, in truth, it can't tell you whether you've reached 940 people one time or 1 person 940 times. But, bear with me… as a point of comparison among various types of media, it's still a useful tool.)
There is also a measurement called "cost per thousand" (CPM) which tells you what you'll pay to reach 1,000 people in your market area. Either CPP or CPM can be helpful in determining the value of a particular media vehicle.
Why? Because CPP and CPM are really the only way to compare different types of traditional media – like radio, TV, cable, billboards, newspaper, and print. Even though each of these delivers your message in a different way, all of them are able to measure reach (i.e., how many people are seeing/hearing/reading your message). So, you can look at the CPP of any proposal to determine its value compared to everything else you've purchased.
Once you've done that, it's up to you to determine if you want to pay an extra premium that, say, the local CBS affiliate is charging, just so you can have customers see and hear your message… or the extra cost that comes with a radio morning show host do a live endorsement of your product… or be on a billboard with the perfect location relative to your store. All of those things have a value that's difficult to put a number on. Just keep in mind that the second or third best TV network in your market, or the third or fourth most popular radio stations, or the billboard that's not quite in the eyes of every driver each morning, may each offer greater value from a CPP or CPM standpoint. In fact, you may be able to pay less and yet be a household name to a greater number of radio listeners or TV watchers by playing the CPP game.
Something to keep in mind next time you begin planning your media buy!