You are approving next year's advertising plan, and the calendar shows heavy weight in the same weeks your rivals always go loud. The instinct is to match them. This research says the week you choose can matter more than the money you commit. The model behind the study predicts that a detergent brand advertising at twice its usual weekly level would see its sales gain nearly double, from about 4.4% to 8.4%, when its rivals dialed their combined advertising weight down for the week. Same spend on its part. The competitive calendar set the return.
When rivals are on air the same week, your ad's sales payoff can be cut in half. What drives the damage is how many of them advertise, not how much they spend.
In packaged-goods categories like detergent and cereal, how much your sales respond to your own advertising is cut roughly in half once a typical number of competitors run ads the same week. What hurts most is not how much rivals spend, but how many of them are on air at once. Before signing off on next year's advertising weight, ask whether the extra spending is buying you sales, or mostly diluting everyone's ads — yours included.
Data chart
at the same total rival advertising, a brand's sales lift is bigger when fewer competitors run ads the same week, so the number of competing ads matters more than their combined spend.
Key takeaway
Your ads pay off far more when fewer rivals are on air, so count the competing ads, not just your own weight.
Source
Danaher, P. J., Bonfrer, A., & Dhar, S. (2008). The effect of competitive advertising interference on sales for packaged goods. Journal of Marketing Research, 45(2), 211–225. https://doi.org/10.1509/jmkr.45.2.211
Evidence strength: Moderate (1991 weekly Dominick's Finer Foods scanner sales for 9 brands across two Chicago grocery categories, matched to spot-TV advertising data; a market-response model with a brand's ad response allowed to fade as more competitors advertise, plus out-of-sample validation). Generalizes most confidently to mature, frequently advertised packaged-goods categories with heavy competing TV advertising; less confidently to other media, non-grocery categories, other markets and eras, and to any claim about profitability or the causal effect of changing spend.