There are 3 types of terms searched on Google:

1. generic terms. I want to know more about the subject, to write an paper for school, to look for more information.

2. comparison. These guys have money, they intend to buy the product but mostly offline. They use google to check the variants, read the reviews. After they make up their mind, they go either in offline and buy it, either they move to step 3: online buying.

3. buying. These guys knows exactly what they are looking for. They are able to pay online. They look for standardise merchandise, with lowest risk, and they look for the smallest price in the market (or other very powerfull advantage – remember, in online it’s easy to compare offers)

Also, that study shows that people looking for generic stuff usually search 1 keyword, those who want to buy search 4 words in a keyword.

So, knowing the above facts, you should target the last category in order to use google to make money. Targeting 4 words keywords could mean lower CPC, longtail ones. So per total, you will get lower costs and higher revenues.

I’m sorry i don’t remember the name of the study, to give proper credits to the author… They were an US university or something….