Conversion rate
The key metric to evaluate the effectiveness of a conversion effort (accepting a free gift, setting an appointment), reflecting the percentage of people converted into buyers (or subscribers, or whatever action is desired) out of the total population exposed to the conversion effort. For Web sites, the conversion rate is the number of visitors who took the desired action divided by the total number of visitors in a given time period (typically, per month).
For example, the conversion rate of visitors that subscribe to a newsletter = number of visitors divided by number of subscribers. If a website has 10,000 visitors and 500 subscribe, the conversion rate equals 1 in 20.
