At 06:36 PM 6/9/2007, Marco wrote: >On 6/9/07, Robert A LaBudde <[EMAIL PROTECTED]> wrote: > > At 12:57 PM 6/9/2007, Marco wrote: > > ><snip> ><snip> > >Hmmm I'm a bit confused, but very interested! >So you don't use the R "ecdf", do you?
Only when an i/n edf is needed (some tests, such as ks.test() are based on this). Also, I frequently do modeling in Excel as well, where you need to enter your own formulas. ><snip> > > Also remember that edfs are not very accurate, so the differences > > between these formulae are difficult to justify in practice. > > > >I will bear in min! My first interpretation was that using some >different from i/n (e.g. i/(n+1)), let to better individuate tail >differences (maybe...) The chief advantage to i/(n+1) is that you don't generate 1.0 as an abscissa, as you do with i/n. But the same is true of (i-0.5)/n, and it's more accurate. Unless you need to do otherwise, just use ecdf(), because it matches the theory for most uses, and it almost always doesn't matter that it's slightly less accurate than other choices. ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: [EMAIL PROTECTED] Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causas scire" ______________________________________________ [email protected] 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.
