That is a generous offer. Our guess was that there were not en=
Alain,=0A =0AThat is a generous offer. Our guess was that there were not en= ough observations to model the varience for each of the cells so we tried m= odeling with different combinations of the cells but that still didn't help= . I ran the analysis in 2000-2001, two computers ago, so it may take a whil= e to find the files and my notes.=0A =0AJohn=0A=0A=0A----- Original Message= ----=0AFrom: Highland Statistics Ltd. <[EMAIL PROTECTED]>=0ATo: ECOLOG= [EMAIL PROTECTED]: Wednesday, March 14, 2007 3:33:56 PM=0ASubject:= Re: [ECOLOG-L] Dealing with non-normal, ordinal data for 2-way ANOVA with = interactions=0A=0A=0A>You seem a trifle sensitive about models and modeling= - statistics =0A>are just tools.=0A=0AFully agree......but these tools tha= t have to be applied correctly.=0A=0A> It makes no sense to say that somet= hing is wrong with the data.=0A=0AI see data sets all the time that are wro= ng; mistakes, typos, wrong =0Acoding of categorical variables, blanks, impr= oper variable names, =0Aetc, etc. These can make a GLM routine crash.=0A=0A= >Either the program works for its intened purpose or it doesn't.=0A=0AHere = is another reason for non-convergence: models with interactions =0Aapplied = on highly unbalanced data; not enough observations in a =0Aparticular two- = or three way interaction combination.=0A=0A>If one of the statisticians who= helped debug the program for SAS and =0A>another professional statistician= /programmer cannot get the program =0A>to work with a data set I'd say that= the functionality of of the =0A>algorithm depends on the data set - it is = a tool that sometimes =0A>can't handle the data.=0A=0AImproper application = of a particular method, over-complicated models =0Awith too many parameters= , or "funny" things with the data comes to =0Amy mind first. I have even s= een people applying a Poisson GLM on =0Anegative data, and wondering why it= crashed.=0A=0APerhaps you are willing to upload your data to a website, so= that we =0Acan all have a go at it? That would solve this discussion for o= nce =0Aand for all. Else we will never know why, and how you managed to =0A= crash the GLM routine in SAS.=0A=0AAlain=0A=0A=0A=0A=0A=0A=0A=0A=0ADr. Alai= n F. Zuur=0AFirst author of:=0A=0AAnalysing Ecological Data (2007). Zuur, = AF, Ieno, EN and Smith, GM. =0ASpringer. 680 p.=0AURL: www.springer.com/0-3= 87-45967-7=0A=0AAnalysing Ecological data using GLMM and GAMM in R. (2008).= Zuur, AF, =0AIeno, EN, Walker, N and Smith, GM=0ASpringer.=0A=0AOther book= s: http://www.brodgar.com/books.htm=0A=0AStatistical consultancy, courses, = data analysis and software=0AHighland Statistics Ltd.=0A6 Laverock road=0AU= K - AB41 6FN Newburgh=0ATel: 0044 1358 788177=0AEmail: [EMAIL PROTECTED] m=0AURL: www.highstat.com=0AURL: www.brodgar.com
