In a recent analysis of PPM ratings, we determined that cume has a bigger impact on share than either TSL or occasions. The natural follow-up question is the relationship between cume and TSL/occasions.
Is it true that cume and TSL are inversely related, that stations can't have a large cume and high TSL? More importantly, can a station grow both cume and TSL at the same time, or does one go down as the other goes up?
It’s a much more complex issue than you might think.
Returning to the rating data-set we used in the previous posts, we plotted cume against TSL. (A graph of cume versus occasions would look very similar.)
The key word, however, is tend. While the relationship tends to be inverse, it isn’t absolute. There are stations that have both above-average cume and above-average TSL.
In long-term trend analyses, Harker Research has also found that growing stations tend to increase cume and TSL at the same time.
In fact, we have found that a good way to differentiate real growth from the more common month to month random fluctuations is to see whether both cume and TSL are growing.
If you see a spike in TSL without a spike in cume (or vice versa), it is probably a wobble. If you see both TSL and cume moving up, it is more likely to be real.
This is also true with downward trends, but more often with a lag between the two measures.
It stands to reason that TSL and cume would both grow for stations on the rise. The same elements that attract new listeners to a station also encourage existing listeners to tune in more often.
More occasions equal higher TSL. Consequently, cume and TSL grow concurrently.
One Radio Insights reader questioned whether external marketing was the only way to grow cume. It isn’t the only way, but it is an efficient way.
In diary markets, it is particularly difficult to grow an audience without external marketing.
The goal of external marketing is to raise a station from phantom status to reported status by raising the station's top-of-mind awareness. You really haven’t gained a listener. You’ve gained a reported listener.
With PPM, listeners are replaced by exposed panelists. The meters pick up “drive-by” exposure, a few minutes at a time. That’s why cumes are higher with PPM.
External marketing is just as important in a PPM market, but it’s goals are different.
With PPM, every listener is essentially a phantom listener. You never know whether a panelist really listened to the station, or simply came in aural contact with it.
External marketing still works by raising top-of-mind awareness, but less directly.
While the goal in a diary market is to directly influence the diary keeper’s actions, with PPM you don’t care whether the external advertising works on the panelist or those around her.
The goal of external advertising in a PPM market is to grow the tent. The bigger the tent, the more people it can hold.
The more people in the tent, the more likely somebody in the tent will be listening to the station and the greater chance that a panelist will be exposed.
This difference between goals means that while external marketing is important in both diary and PPM markets, the messages need to be different.
That will be the subject of a future post.