Effective advertising is about exposing a target audience to enough repetitions of a message to inform, persuade, or drive action. The challenge with legacy media like TV, radio, and print advertising is that there’s significant waste – you’re also paying to share your message with voters outside of your target audience. But that’s the tradeoff. You’re reaching a large audience but somewhat imprecisely.
Primarily due to a lack of understanding about the technology, too many campaigners think that advertising online functions differently. But your goal is still the same – reach an audience with a repeated message.
Eliminating any possibility that someone outside of your target audience sees an ad is the wrong way to target online ads. In fact, this approach actually diminishes the impact of your efforts because parts of your target audience will always be missed if your campaign is too restrictive in its parameters.
The Wrong Way to Target Ads

Rather, digital targeting gives you greater efficiency over analog, broadcast advertising by reducing the total number of off target impressions.
The Right Way to Target Ads

If your online ads aren’t targeted correctly, you run the risk of keeping your message away from the right voters. Understand the limitations of your targeting options and recognize the most effective approach is to reduce – not eliminate – wasted impressions.