Mostly: Classical

[amarksp]

ok Louis, may have figured out where most of variance is...

GFMS report dated Oct 17th could not have included ECB Press Release dated Oct 18th that reported gold sales through Oct 14th. Thus, GFMS report likely just included the data for 9/30 and 10/7 periods (and not 10/14).

Thus, I derive central bank sales as of 10/7:
Per GFMS = 12 Tonnes
Per ECB Press Release = 10.86 Tonnes (3.04+7.82)

still noodling around with a spreadcheat...

FWIW, the Euro POG 393.124 is what ECB used to value gold as of end of the quarter (9/30), not the average price of central bank sales for the week. Think I will just eyeball a 5 day moving average chart to determine average weekly Euro POG of central bank sales...
http://stockcharts.com/def/servlet/SC.web?c=$GoLD:$XEU,uu[h,a]daclynay[da][pb5]&pref=G