A decay factor is an estimate of how long it takes an advertisement to fade from the minds of consumers, using exponential modeling. Researchers with an interest in advertising efficacy have noted that advertisements tend to follow predictive modeling, making it possible to determine how long an advertisement will have an effect on the public. They use exponential modeling, where a steady decrease occurs in direct connection with the original value of the advertisement. Original values can be calculated by looking at the depth of exposure, how many people saw the ad and where.
This is also sometimes known as half-life, a reference to a specific type of exponential decay seen with radioactive elements. Advertising half-life can vary between two and seven weeks in most cases, although there are outliers outside this model. Some advertisements also behave unpredictably, and may not follow the decay factor models used to explain how consumers interact with the content they encounter in magazines, on billboards, and in other locations.
Over time promotions can lose their strength if consumers are not exposed again. They may forget key details of an ad, like product or brand, pricing, and function. This often translates into changes in their buying habits; the consumer who would have sought out Brand X toilet paper a week after seeing an ad for it, for example, might not think of it in three weeks. Advertising firms must consider the decay factor when they decide how and where to place ads.
Good ad placement can be key when considering decay factor. The right timing puts features in front of large audiences. This results in hot competition for coveted ad slots, like those on prime time television broadcasts. Advertisers know large numbers of viewers will be tuning in and want a chance to increase the original impact of an ad as much as possible. They may also opt to repeat over several time slots and weeks to keep the content fresh in the minds of potential consumers.
Design and messaging can also be important. Decay factor can shift depending on how an ad is presented. Strong, interesting, or quirky material may stand out more for consumers. This can be particularly true of viral advertising, where consumers may not be aware they are looking at an ad. Materials presented in environments like games on social networking sites can stick with viewers longer because they are associated with activities like connecting with friends or using familiar resources.