If you take the
Average Cost per Click
that a domain advertises on, add them all up, and divide by the total number of keywords, you will have the Avg Cost/Click for a domain. For example, if a domain advertises on 3 keywords with Avg Cost/Clicks of $1, $2, and $3, respectively then the Avg Cost per Click for the domain would be $2.
How You Can Use It
You can use Avg Cost/Click as a barometer to gauge the relative efficiency of a competitor’s advertising campaign. A domain that buys lots of low traffic, low cost long-tail keywords will have a lower Avg Cost/Click than a domain that buys fewer high traffic keywords. The former is a domain that is executing efficiently.
When you see that a domain’s Avg. Cost/Click change or change percent is increasing, that doesn’t necessarily mean that they are getting less efficient. It probably means that they are getting more competition.