At 09:56 AM 2/8/2000 -0500, Lary Jones wrote: ... >First of all, it is often forgotten that deciding to replace missing values >depends on the assumption that the missing values occur randomly. I think >this rarely happens. ...

Let me add the following to my previous note.

My background in social psychology and measurement has made me into a bit of a curmudgeon about replacement of missing values. I would be most interested to hear the opinions of others. In my woeful ignorance of recent literature, I wonder if anyone has developed a technique for assessing the randomness of missing values within the rectangular array of a list of variables over all the subjects. My opinion is that missing value replacement is only justified if we know that the pattern of missing values is haphazard (unrelated to the row or column of the data matrix).

I will be researching this, but would appreciate any knowledge that others might have.

_______________________________________________________ Lary Jones % Statistical Computing Analyst Computing Services % .......................... Binghamton University % LJones@Binghamton.EDU Binghamton, NY 13902-6000 % (607) 777-2614