In the search world, we calculate click-through-rate (CTR) as clicks divided by impressions, and it measures the number of times an ad was clicked versus the number of times it was viewed. This works a bit differently for Facebook. Here, a user can see the same ad multiple times per day, which leads to both a true versus unique CTR for that ad.
For example, assume you and I see the same ad on Facebook 10 times a piece, and at the end of the day, you click on it and I don???t. This would equate to one click on 20 impressions, or a CTR of 5%. But, if we were to look at unique CTR, we each saw one ad throughout the day, you clicked, and I didn???t. This would equate to one click on two unique impressions, or a CTR of 50%, which is obviously quite different.
Looking at this on a larger scale over the course of a week, we see the following trend:
If we analyze this campaign based on true CTR, we might assume a steady trend of clicks to impressions. But, if we include the unique CTR in the analysis, we see an increasing trend in the proportion of clicks to impressions (or user interest), which starts to decrease after the third day.
This brings up the next line of questions in regards to ads on Facebook. When does ad fatigue kick in? At what point do we need to refresh ads or images to interest the user again? At Efficient Frontier, we???re currently testing these questions and uncovering some interesting findings, so stay tuned for more on this topic.
Senior Account Manager