Big question
Are you buying efficient ratios, or enough reach for long enough to grow profit?
The position
Show marginal return and total profit contribution together, including delayed effects. Use the excess share of voice argument to defend share, never to promise a number to a finance director.
Why it is live
Efficiency ratios improve as you spend less, so a plan can look better while the business grows more slowly. The IPA argued in May 2026 that small thinking is killing advertising, restating its earlier work on the cost of underinvestment.
The case for buying the reach
ContestedCategory-level evidence supports broad reach for growth, and the excess share of voice rule is widely reproduced as buying about half a point of market share a year.
The case against
UnknowableThe direct response evidence is real, the coefficient is stale, a weakening to something nearer 0.4 has been claimed and could not be verified, and no published function runs from a quantity of exposure to a change in behaviour at brand level.
Where the weight sits
For reach as the growth argument and efficiency as the harvesting argument, with the coefficient not defensible as a number. The direction holds and the arithmetic does not.
What would change this
A fresh analysis on a current dataset with the method published, or a platform releasing category buying frequency data that lets anybody test the light buyer claim directly.
Where this is taught
- 2.2 The only respectable method needs a number nobody has
- 3.1 Where a strategic audience comes from
- 3.2 Three audiences, and the second join nobody teaches
- 4.3 No method from a proposition to a channel, and a good argument that there should not be one
- 1.3 How the split gets decided, and who benefits from the definition
Strategy and Planning
A note on this question
the excess share of voice coefficient itself is taught in TV and Video at tv-c01-m3, which is where the contested versions sit. It is listed as an anchor because a question that crosses books should say so.
Sources
- IPA, small thinking is killing advertising, 27 May 2026secondary
- IPA Profit Ability, 23 May 2024secondary