-----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of Steve Lianoglou Sent: Tuesday, August 18, 2009 7:25 AM To: John Kane Cc: r-help@r-project.org; Steve Murray Subject: Re: [R] Replacing NA values in one column of a data.frame
...** But do NOT do this.*** Unless you are using R to prepare your data for some other statistical analysis system (most unwise), there is **never** any reason in R to replace NA's with nonsense numerical codes -- and a great many reasons NOT to do this, to whit: 1) NA's are a special value in R (actually many, of different types) with extensive built-in capabilities to handle them properly, deal with them (often automatically) in fitting functions etc. Recoding to a nonsense numeric defeats all this careful machinery. 2) You are just begging for trouble by using nonsense numerics: if you forget your coding or someone else uses your data who's not aware of it, voilá ! -- you have just guaranteed that data analyses will be partial or complete garbage. Finally -- a request to well-meaning helpeRs: Just because you CAN do something in R statistically or programmatically does not mean you should. When someone requests something that you believe is the wrong thing to do, I think it within the bounds of both R etiquette and professional practice to tell them NOT to do it and explain why not. Of course, sometimes such admonitions are themselves ill-advised (as this may be), but an open, courteous, professional exchange on the issue will itself be informative to useRs. Cheers to all, Bert Bert Gunter Genentech Nonclinical Biostatisics ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
