This seems live a very good post about the differences between the length of a search query and the conversion rate of search queries from SEO Speedwagon

I decided to do a very unscientific mutation of the report. I overlaid conversion data from a campaign I’m working on against the OneStat query-length data, just to see what would happen:

(source of pink data: OneStat. source of blue data: Intrapromote.)

If you remember much about calculus, you know that if the two lines overlap exactly, that doesn’t mean that two-word phrases, for instance, convert better than three-word phrases. Instead, if the two lines overlap exactly, it means that all query lengths convert at relatively equal rates. For example, if 35% of all queries and conversions come from two-word queries, and if 15% of all queries and conversions come from four-word queries, then two-word and four-word queries convert at the same rate.

Therefore, the noteworthy locations on the graph are where the two lines diverge most dramatically. In my example, one- and two-word phrases convert at higher rates than their respective query volume rates.

Practically speaking, what does this mean to a search campaign?

In my case, it’s an indicator that two-word phrases are a revenue-rich target because they have both the raw search numbers and the conversion rate to pay off. Single-word terms have great conversion rates but far fewer raw searches.

Note that this is extremely unscientific. It pits worldwide query string length data against conversion data in a specific vertical. So I certainly need to crunch more numbers. But it gives some good hints about where to look to increase traffic and conversions.

I’d go after the two and three and four word queries.