Effective frequency: activate bullshit detector

You probably know there are two dimensions in buying media: reach (% of your audience who see your ad) and frequency (number of times they see it). With a limited budget, there’s a trade-off. You can buy one spot on Australian Idol (high reach) or for the same money you can buy ten spots on Good Morning Australia (high frequency).

Many television and radio stations still talk to clients about the need to reach customers a certain number of times. Warning! If you are a client, this is not a good way to buy media. The stations base their argument on the notion of “effective frequency” which says you have to see a commercial a certain number of times before it is effective. Intuitively, you know this is crap. Mathematically, it’s also crap. Here is a reasonably technical award-winning article from the current darling of the US media world, Erwin Ephron and Melissa Heath which explains why. Summary: get on air as many weeks as you can. Maximise your reach by buying more than one station. Don’t let any suit tell you you need to reach consumers a certain number of times.

The Ephron media buying strategy (he calls it Recency) now has some currency in Australia but the man who first effectively argued against “effective frequency” and the “S-shaped response curve” worked in Wodonga, Australia in the 1980s.

A British-born mathematician, Chris Talbot, developed this argument while working for Uncle Ben’s Australia (Mars Group) who were at the time buying all their media through George Patterson Pty Ltd. (then the largest agency in Australia and now part of the Bates Group). He forcefully and effectively argued that the company adopt it and then challenged the best resourced agency in Australia to re-buff it. They could not.

Not only did Talbot argue this line fifteen years before Ephron made a name for himself in America, he wrote a program which re-allocated the company’s spots to give each brand the maximum reach per dollar spent.

Chris Talbot died young about ten years ago. He deserves recognition for his application of scientific principles to marketing and as a pioneer in media buying. Wherever you are Chris, you were right. There is no such thing as an S-shaped Response Curve.



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