Which metric is most commonly used to assess the cost efficiency of reaching an audience?

The metric most commonly used to assess the cost efficiency of reaching an audience is CPM, which stands for Cost Per Mille (thousand). CPM focuses on the cost of displaying the advertisement to a thousand impressions, providing a clear measure of how much it costs to reach that audience segment. This allows advertisers to compare the cost effectiveness of different ad campaigns, media placements, or strategies across various platforms and audiences.

When evaluating advertising campaigns, understanding the CPM enables advertisers to calculate their return on investment by analyzing how many people their budget is reaching. A lower CPM typically indicates a more cost-efficient method of reaching a large audience, making it a key metric for strategizing and optimizing ad spend.

In contrast, other options like GRP (Gross Rating Points) measure the overall impact of an ad campaign based on reach and frequency but do not directly address cost efficiency. Reach refers to the total number of unique individuals exposed to the ad, while frequency pertains to how often those individuals see the ad. Although these metrics are crucial for campaign effectiveness, they do not provide a direct cost measure necessary for evaluating financial efficiency.