Which of the following is NOT a common metric used to measure ad performance?

The correct answer is that time spent on social media is not a common metric used to measure ad performance. In the context of evaluating the effectiveness of advertising campaigns, metrics like click-through rate (CTR), return on ad spend (ROAS), and cost per acquisition (CPA) provide direct insight into how well an ad is driving user engagement and generating revenue.

Click-through rate (CTR) measures the ratio of users who click on an ad to the number of total users who view the ad, helping advertisers understand the effectiveness of ad creatives and targeting. Return on ad spend (ROAS) quantifies the revenue generated for every dollar spent on advertising, serving as a crucial metric for assessing the profitability of ad campaigns. Cost per acquisition (CPA) calculates the total cost associated with acquiring a customer, which is essential for evaluating the efficiency of conversion strategies.

In contrast, while time spent on social media can provide insights into user engagement with the platform itself, it does not directly measure the performance of individual ads. It lacks the specific financial or engagement-related metrics critical for determining the success of ad campaigns. Therefore, it is not typically considered a common metric for evaluating ad performance.