Hi Roger,
I saw an old plot on the website.
Here is an updated version of the Orion vs Mindsong reg
variance plot.
(Note: the colors are reversed from the earlier
plot.)
The variance is calculated for each reg for a calendar
quarter.
The first quarter plotted is the third quater of 1998. The
last is the third quarter of 2004.
Here are some notes (just for completeness) on this old
story...
The mean of the Orion quarterly variances is
.999925
The Orion average deviation from expectation is 7.5 x
Exp[-5]
Student t pval = 0.016 for the quarterly
values.
The mean of the Mindsong quarterly variances is
1.00073
The Mindsong deviation from expectation is 7.3 x
Exp[-4]
Student t pval = 0 (i.e., improbably small)
So the magnitude of average bias is a factor 10 greater
for the Mindsongs compared to the Orions. The Orions are significantly biased,
on average, but only marginally so: we get a pval of .02 after nearly 6 years of
data.