nordlead on 21 May 2009
Obviously you don't know too much about how the website works.
Data comes in, and weekly numbers are generated. More data for past time periods come in, and the data is refined. This causes previous weeks to go up/down depending on the additional data for past weeks (financial results for example could show VGChartz is overtracking).
The grand total reflects the best estimate (since all the numbers are estimates) of total sales up to the latest weeks results.
This website's only bias is reality.
