An effective reach curve shows the portion of an audience which has been exposed to programming at various levels of frequency. It shows, for example
- What percentage of an audience was exposed to any portion of at least one quarter hour of a set of quarter hours
- What percentage of the same audience was exposed to at least two quarter hours
- Etc.
The figure below shows the effective reach curve for an 8 week campaign for a luxury car. The ads aired on both broadcast and cable television. The curve shows that 69.2% of the sample adults 18-49 saw one or more ads for the car, 30.7% saw three or more ads.
Figure 1 - Luxury Car Effective Reach Plot
Generally, for advertising campaigns, one wants a fairly steeply sloping effective reach curve. A steeply sloping curve indicates relatively large numbers of people are exposed to an advertising message a few times, but relatively few are exposed many times. It is believed by some that there is a point of
diminishing returns
, where additional exposures to an ad do little to influence either
recall
or purchasing.
The data behind the figure is shown in the table below. Of a total of 941 adults 18-49 in the sample, 290 did not see any of the ads, 204 saw exactly one ad, 158 saw exactly two ads, etc. Only one person was exposed to more than 14 ads. This person saw 23 ads!.
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