Data: Tue, 30 May 2006 16:08:26 -0300 (ART)
De: Milton Cezar <[EMAIL PROTECTED]>
Assunto: R: Piecewise (broken stick) models in R && Stats for groups
Para: [EMAIL PROTECTED]
Chris Barker and everyone
Thanks for your fast replay.
Regarding the descreptive Stats, I can compute it for the full dataset, but I
can´t comput it for groups of that.
I used mean ( Rainfall [year==1980] ) without problem. But how can I get the
mean Rainfall for Year==1980 AND Site=1; Year=1980 AND Site=2 etc.
Regarding my question for Pieacewise Regression model It can really be done
with liner models functions. In fact, the results are a set of models that work
bether in different range of an X variable (for X varying 0 to 0.15 use
model_1; for 0.16 to 0.46 use model_2... for X>0,47 use model_3 etc.
Sorry for my broken english,
Regards a lot,
Miltinho
From: Barker, Chris [SCIUS]
To: 'Milton Cezar'
Sent: Tuesday, May 30, 2006 3:47 PM
Subject: RE: [R] Piecewise (broken stick) models in R
You can get descriptive statistics with mean(), var() or summary().
AS to broken stick, I can only speculate that's a variation on a regression.
You may need to be more specific in your questions to the list, as I suspect
its something easily done in the linear models functions.
Chris Barker
Associate Director, Biostatistics
Scios Inc.
6500 Paseo Padre Parkway
Fremont, CA 94555
Tel 510 248 2439
Fax 510 248 2451
==============================
From: [EMAIL PROTECTED] On Behalf Of Milton Cezar
Sent: Tuesday, May 30, 2006 11:42 AM
To: [email protected]
Subject: [R] Piecewise (broken stick) models in R
<< File: ATT17883177.txt >> Hi there,
I´m a newbie in R and I´m looking for some advice how to teste Piecewise
(Broken Stick) models.
I´have another simple question: how can I compute descriptive statistics for
data grouped for two or more variables? See below, please.
Year Site Repetition rainfall
1980 1 1 ...
1980 1 2 ...
1980 1 3 ...
1980 2 1 ...
1980 2 2 ...
1980 2 3 ...
1990 1 1 ...
1990 1 2 ...
1990 1 3 ...
1990 2 1 ...
1990 2 2 ...
1990 2 3 ...
I´d like to compute the mean rainfall for each YEAR * SITE combination.
Kind regards,
Miltinho
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