Re: Coding "missing values" - standards, customs, tricks of the trade?

In article <DL33Dv.EoI@world.std.com>, infosrfp@world.std.com writes: > > Do any standards exist for the representation of "missing" values? > Failing that, any widely used customs? Or tricks of the trade? > > Ten years ago, while working with medical and scientific data > for which partial results were computerized pending final > reports from a laboratory, I was accustomed to flagging such > "missing, but expected" values with a project-specific code; this distinguished > "missing" cases from values that were already firmly known to be > zero, null, void, "not applicable", lost, unobtainable, or whatever. > > At that time I took a quick look and could not find evidence of > any standards by which to design for this aspect of data management. > Having recently become re-involved with some datasets sharing this > characteristic of having an unpredictable arrival date for some values, > I wonder what standards or approaches may be current practice. > Pointers to textbooks, journal articles etc. would be welcome. > Hi Steve, Are you potentially looking at NULL? That's considered a non-value so to speak... Pablo Sanchez | Ph # (415) 933.3812 Fax # (415) 933.2821 pablo@sgi.com | Pg # (800) 930.5635 -or- pablo_p@corp.sgi.com =============================================================================== "I am accountable for my actions." http://reality.sgi.com/employees/pablo_corp - pablo