Weekly data was available for the first three weeks of December, but the monthly numbers that are the most accurate and include all sales would not have been available until mid January. As David pointed out he [Ron Sanders] never says he saw NPD data for December, but he would have seen it for October and November.
Speaking of numbers, I just noticed how Bill Hunt excluded XBOX add on drives from the NPD numbers that are shown on his site and a few posts earlier. That would NOT have changed the final outcome (Blu having a large hardware lead), but it would have made the numbers look a lot better for HD DVD. I am not wanting to rehash the age old argument "should a PS3 be counteed as a standalone player", but since inception the XBOX add on has been counted as a standalone player when sales are reported since it can only play HD DVDs. Bill chose to exclude them from the charts he created which make them inaccurate compared to how NPD sales data has always been reported.