What key metric should advertisers monitor to measure ad campaign effectiveness on Facebook?

To effectively measure ad campaign effectiveness on Facebook, it's essential to consider a variety of metrics, as they each provide valuable insights into different aspects of campaign performance. Total impressions indicate how many times the ad has been seen, which is important for understanding overall reach. Cost per click demonstrates how much advertisers are spending for each user that clicks on their ad, giving insight into the efficiency of the ad spend. Click-through rate (CTR) is a crucial engagement metric that shows the percentage of users who clicked on the ad after seeing it, which helps in assessing how compelling the ad is to the audience.

By monitoring all these metrics together, advertisers can get a comprehensive view of their campaign effectiveness, from reach and engagement to cost efficiency. Analyzing them in isolation could lead to a skewed interpretation of the campaign's success or areas needing improvement. Therefore, evaluating all of the above metrics provides a well-rounded perspective that is essential for optimizing advertising strategies on the platform.