I was calculating the year to date sales figures for US (and all other regions) and I found out that the VGChartz data reveals the XB1 USA as follows...
XB1 Cumulatve sales end of 2013 : 1 844 460
XB1 Cumulative sales by 1 Feb 2014 : 2 126 370
XB1 January 2014 Sales : 281 910
PS4 January 2014 Sales : 371 429
The NPD January sales data reveals 143K XB1 sold in January, (where PS4 must nearly double the XB1 sales) which seems to significantly contradict the figures above. Even if the number of weeks included may be 5 instead of 4, this should not change the sales ratio as much. So XB1 is most likely overtracked.
Playstation 5 vs XBox Series Market Share Estimates
Regional Analysis (only MS and Sony Consoles)
Europe => XB1 : 23-24 % vs PS4 : 76-77%
N. America => XB1 : 49-52% vs PS4 : 48-51%
Global => XB1 : 32-34% vs PS4 : 66-68%