NavList:

Dave

That would agree with my suggestion if and only if the cocked hat was
equilateral. Otherwise the contours of equal probabilities are
eccentric so as you can imagine (under these assumptions of Gaussian
errors) you are more likely to be in one direction than another
putting the point of maximum probability off the line joining the two.

But as you say, the line between them is the quickest you can do
graphically by hand, and you just would trust it less with a very high
aspect ratio cocked hat.

Bill