Effective frequency: there and back

Simon Broadbent, The Brand Consultancy, reviews three decades of thought, and presents some suggestions of his own

Simon Broadbent

Effective frequency has been a controversial subject ever since it was first formulated. This discussion starts at the beginning of the story in the UK.

In the early 1960s, the buyer's cost per thousand was of course always examined - post-campaign, had he got the expected ratings for the money spent? But that was not the only criterion, for the following reason.

The crafty buyer was tempted to go for cheap off-peak time. This meant low total cover since the elusive light viewers - often a valuable target - rarely watched off-peak. It also meant buying times of lower attention. We could be confident our campaign had no effect on those who had not seen it. In order to push up cover, and to stop the buyer spending too much off-peak, we set a second criterion. This was a cover target over a specified period. Four weeks was the usual reporting period, as the longest interval for which we had adequate samples.