Dear Seppo: you are not the first to make such a comment. I'd say that MAR is one of the few terms in the area I like, since it at least has a well-defined meaning! It was originally coined in Rubin's 1976 Biometrika paper, and the rationale was that people were doing analyses ignoring the missing data mechanism that had an implied assumption, and he defined MAR to be that implied assumption. For likelihood inference that assumption is MAR. Since there is another reasonable term for the "randomness" you are talking about, namely missing completely at random, I see no real problem. There is an strong argument that people who write the seminal article should get to define terms, and I think trying to change a definition is asking for confusion.
Concerning other terms, is there an established definition of "informatively missing"? I'd be interested in comments on this. Best, Rod On 29 Mar 2001, Laaksonen Seppo wrote: > I do not like about the term MAR, missing at random. Of course, when it has > been defined, there are no problems. But the direct interpretation of that > term > is confusing, since missingness is not random in this case but conditionally > in > some sense. The term should be something like missing at random conditionally > (MARC) or MAR according to covariates. I am not fully satisfied to those > terms. > What do you prefer? > > Best regards > Seppo Laaksonen > > > ___________________________________________________________________________________ Roderick Little Chair, Department of Biostatistics (734) 936-1003 U-M School of Public Health Fax: (734) 763-2215 M4208 SPH II [email protected] 1420 Washington Hgts http://www.sph.umich.edu/~rlittle/ Ann Arbor, MI 48109-2029
