That is exactly what i say every time i see someone claiming VGC to be wrong or trash. Its an estimate, same as saying its a value based on probability. There is no wrong estimate. Theres more accurate or less accurate.

I just wanted to thank the person who started this thread, and to ioi for explaining how the numbers are determined and what they mean, in terms that I can actually understand. I get it.

If i remember correctly this is bretts side project and not even his bread maker. he has a real job. as for an office? what... who would be in the office? brett is from UK. Most users are in US as well as the staff. As for accuracy, they arent accurate at all. If we cut VGC off from any outside information the numbers would be a train wreck. Only reason it is slightly accurate is from adjustments when they happen. Even if they were more accurate than they really are it doesnt mean they get info from retailers. No retailer will give a site like VGC any meaningful information. Its probably against corporate policy. However, knowing previous trends in sales makes it rather easy to guess other sales. When Wii U came out Brett said he used past sales of (i forget which console. I want to say the Ps3 and 360) to determine Wii U trends and it translated horribly because Wii U didnt perform like the console he chose.

No fallacy.... Don't see NPD running a site like this =] and caring to explain what they are doing for people that aren't even paying for them.

im sure if you meet someone who works there they will be glad to discuss to you their work. it is a fallacy because parts dont make the whole and vice versa. NPD and VGC cant show a human trait like humor since they arent human

Its a language construction to give human characteristic to things.

Prob didnt have anything or little to do with agreement and more to do with he was still working on the numbers.  it was adjusted roughly 50k (which i even agreed to in PM).  The complaints was arguing anything from 100k to 1m undertracked.  Not one person offered factual evidence or said it was undertracked by a few thousand.

To people suggesting a number like 370022 for a given platform in a given week be rounded to 370000: it wouldn't be correct. If calculations bring to a result of 370022 ± error margin, rounding it to 370000 ± error margin wouldn't be the same. Look at the first message of this thread, it's explained quite clearly: that 370022 value is the midpoint of the probability curve of the extrapolation of sales data collected that week. BTW most probably a rounding to the closest unit already happened, as sales are integer numbers, start values are integers and final values must be too, but intermediate values very often won't and calculations will be made keeping all the available decimals in every intermediate result, and rounding will happen only at the end to limit the growth of rounding error, that would just be added to the error already present in the extrapolation.
I'm puzzled, I thought that some basic rules for rounding and about measurement errors were taught also in high-school physics courses all around the world, not just at university.

And aparrently you haven't learn them since you want to use more signficance numbers than the tolerance permit.

My only thing Brett, it seems that has times passed by the last couple years, the numbers got worst. It seems you have been putting less work into these numbers than before and it shows.