Wearout effects in target marketing

Given that most advertising campaigns attempt to target advertisements to a specified demographic or product usage group, it seems reasonable to demand a high correlation between exposure to the media and membership of the target group. A surprising result of this research is that this correlation peaks and then declines as the number of insertions or spots in the campaign increases. That is, there appears to be a wearout effect of target market advertising beyond a certain exposure level. A simple formula is derived that gives the optimal number of insertions in the advertising campaign for the strongest link between media exposure and membership of the target group.