Thats “The Long Tail” to my left. Its called a Pareto distribution. Chris Anderson, and everyone who lusts for long tail economics (of which I’m one), like to talk about the never ending nature of the tail, about how even way out to the right there is always going to be at least one person. And yeah, for the most part thats true, but at least in search traffic distribution a power-law curve like the Pareto presents a calculable point of diminishing returns.
If you took a set of keywords, each with the number of searches for it per day, and graphed them, with the keywords on the x axis listed with the most popular keywords on the left, and the traffic on the y axis you’d get the top graph. The head and the tail.
That second graph there on the bottom is the cumulative percentage of the traffic. One of the key ideas of this type of keyword traffic distribution is the point where that line crosses 80% of traffic on the y axis, in the keyword niches I studied it happened somewhere between 20% and 40% of the keywords on the x axis. Essentially, what percetange of the total number of keywords account for 80% of the total traffic of the set. My research indicates that for most niches between 20% and 40% of the top keywords account for 80% of the total traffic.
Update: the images weren’t working. I’ll show you some real examples derived from specific niches…