Recently there has been talk of a new metric within the PPC industry: conversions per impression. I first read about this metric from Chris Crompton of Search Engine Land.
In my view, this metric represents the overall effectiveness of your PPC campaign. The click-through rate (CTR) measures how relevant your ads are to user search queries. The conversion rate tells you the percentage of visitors who complete your predefined goals once the ads are clicked. These are important metrics, but it may be time to consider conversions per impression (CPI) as well. Let’s take this example: