lme nesting/interaction advice
On Mon, May 12, 2008 at 10:50:03AM +0100, Federico Calboli wrote:
On 12 May 2008, at 01:05, Andrew Robinson wrote:
On Mon, May 12, 2008 at 10:34:40AM +1200, Rolf Turner wrote:
On 12/05/2008, at 9:45 AM, Andrew Robinson wrote:
On Sun, May 11, 2008 at 07:52:50PM +0100, Federico Calboli wrote:
The main point of my question is, having a 3 way anova (or ancova, if you prefer), with *no* nesting, 2 fixed effects and 1 random effect, why is it so boneheaded difficult to specify a bog standard fully crossed model? I'm not talking about some rarified esoteric model here, we're talking about stuff tought in a first year Biology Stats course here[1].
That may be so, but I've never needed to use one.
So what? This is still a standard, common, garden-variety model that you will encounter in exercises in many (if not all!) textbooks on experimental design and anova.
To reply in similar vein, so what? Why should R-core or the R community feel it necessary to reproduce every textbook example? How many times have *you* used such a model in real statistical work, Rolf?
There is a very important reason why R (or any other stats package) should *easily* face the challenge of bog standard models: because it is a *tool* for an end (i.e. the analysis of data to figure out what the heck they tell us) rather than a end in itself.
But a tool that mostly (entirely?) appears in textbooks.
Bog standard models are *likely* to be used over and over again because they are *bog standard*, and they became such by being used *lots*.
Well. I have documentation relevant to nlme that goes back about 10 years. I don't know when it was first added to S-plus, but I assume that it was about then. Now, do you think that if the thing that you want to do was really bog standard, that noone would have raised a fuss or solved it within 10 years?
If someone with a relatively easy model cannot use R for his job s/he will use something else, and the R community will *not* increase in numbers. Since R is a *community driven project*, you do the math on what that would mean in the long run.
Fewer pestering questions? ;) Andrew
Andrew Robinson Department of Mathematics and Statistics Tel: +61-3-8344-6410 University of Melbourne, VIC 3010 Australia Fax: +61-3-8344-4599 http://www.ms.unimelb.edu.au/~andrewpr http://blogs.mbs.edu/fishing-in-the-bay/