Back to estimating

A short time ago we had a brief discussion about whether / to what extent XP estimating / planning practices would find support in a Six Sigma environment.  We now have a 6S Black Belt in our midst so I'd like to get back to that discussion.  The specific question at that time was about XP's practice of not committing to more story points for iteration X than were accomplished in iteration X-1.  As a (re)starting position, it seems to me that 6S would probably take a position that the estimate of what would be accomplished in iteration X should be based on a statistical measure of the team's velocity over some window of iterations in the past, where the window is a size greater than one.

In addition to the 6S viewpoint, last week there was a post to the XP list about some research comparing the effectiveness of Function Points and Ideal Engineering Days (IED) as predictors of velocity in an XP environment.  The author's conculsion, based on statistical analysis, was that IED estimates were more predictive.  If substantiated by other researchers, this could be important support for the introduction of XP / Agile practices in a high-ceremony environment currently using Function Points.  The author of that paper has joined us.  I'd like to ask, as a starting point for discussion; have you had a chance to have FP folks review and comment on your work?  What were their reactions?

Best regards,
Bill