Exactly, drkohler. If not higher because they *are* major retailers, some selling 10x as many as the mom and pop stores.

The only possible exception would be if a major chain decided not to share its sell thru information with GfK. But that would, of course, affect all 3 console makers, not just one.

And one other thing.

GfK wouldn't report 'here are 80% of the stores and their sales.  I have no clue how much the actual sales are'.  They would report, as mention, 80% of the stores mean X as total sales, or (tho less likely), here are their sales and X is the number we think is the total based on those sales. 

Why is it less likely?  Consider if ioi said, here are the actual sales I had reported to me, and I estimate that X, Y and Z are the total sales for the consoles.  Even more than now, there would be complaints of how from the actual sales, he got the estimates.  He, GfK and others don't need that headache.

 I'd agree with this comment as well.  Or if VGChartz more accurate, their understanding of how it works in getting its estimates, as well as how the paid ones, like GfK work.  

While it can be frustrating that someone might not understand what you mean, TWRoD, it often means you just need to say it in another way, and like MikeB says, leave out the cheapshots.

(Save those for more subjective topics, like which FPS is the best in terms of music.  :)  ) 

I create this thread because I saw several credible sites backuping my theory and I wanted the answers. I respect ioi and I appreciate his work, so if he said „GFK figures are, and always have been, for 100% of the market based on a sample of 80% - just like every other tracking service.“ I believe him.

From the random person on the internet (not credible): „GfK covers 80% of the market in Germany, but in contrast to Media Create, Famitsu, NPD etc. the rest of the market isn't extrapolated. So these are the sales for the 80% tracked part of the market and the rest isn't there at all.“

People are confused, that's all, ...also, if someone say something, it's either his/her opinion or the fact, but fact must be based on credible source.

Are you sure that's German? I took 4 years of German and I can't read a word of that! LIES LIES LIES I TELL YOU.

It has been a while though. I even visited Austria and Germany 6 years ago. Best 2 weeks of my entire life.