Do traffic and sales generally correlate?

[karomesis]

Increases in traffic cannot be directly connected to sales because it depends on where that additional traffic is from.

Yes, of course, but with a particular source of your traffic are your projections "roughly" accurate? In its respective market segment? If you knew that your blog recieved the majority of the uniques from SE or other filtered blog traffic would that assist you in consistenetly getting a correlation between traffic and sales?

And would you say that bookmarkers provide assistance in determining the correlation itself? Is bookmarked traffic more reliable for projecting sales figures across the board?