Re: [R] Differences in output of lme() when introducing interactions

2015-07-24 Thread John Kane
...@mayo.edu Subject: Re: [R] Differences in output of lme() when introducing interactions The following are in parody (but like all good parody correct wrt the salient features). The musings of Guernsey McPhearson http://www.senns.demon.co.uk/wprose.html#Mixed http

Re: [R] Differences in output of lme() when introducing interactions

2015-07-23 Thread Rolf Turner
On 24/07/15 07:07, Therneau, Terry M., Ph.D. wrote: The following are in parody (but like all good parody correct wrt the salient features). The musings of Guernsey McPhearson http://www.senns.demon.co.uk/wprose.html#Mixed http://www.senns.demon.co.uk/wprose.html#FDA In formal

Re: [R] Differences in output of lme() when introducing interactions

2015-07-23 Thread Therneau, Terry M., Ph.D.
The following are in parody (but like all good parody correct wrt the salient features). The musings of Guernsey McPhearson http://www.senns.demon.co.uk/wprose.html#Mixed http://www.senns.demon.co.uk/wprose.html#FDA In formal publication: Senn, Statistical Issues in Drug Development,

Re: [R] Differences in output of lme() when introducing interactions

2015-07-22 Thread Therneau, Terry M., Ph.D.
Type III is a peculiarity of SAS, which has taken root in the world. There are 3 main questions wrt to it: 1. How to compute it (outside of SAS). There is a trick using contr.treatment coding that works if the design has no missing factor combinations, your post has a link to such a

Re: [R] Differences in output of lme() when introducing interactions

2015-07-22 Thread Rolf Turner
On 23/07/15 01:15, Therneau, Terry M., Ph.D. wrote: SNIP 3. Should you ever use it [i.e. Type III SS]? No. There is a very strong inverse correlation between understand what it really is and recommend its use. Stephen Senn has written very intellgently on the issues. Terry --- can you

Re: [R] Differences in output of lme() when introducing interactions

2015-07-22 Thread Marc Schwartz
Hi, In addition to Terry’s great comments below, as this subject has come up frequently over the years, there is also a great document by Bill Venables that is valuable reading: Exegeses on Linear Models http://www.stats.ox.ac.uk/pub/MASS3/Exegeses.pdf Regards, Marc Schwartz On Jul

[R] Differences in output of lme() when introducing interactions

2015-07-20 Thread angelo.arc...@virgilio.it
Dear List Members, I am searching for correlations between a dependent variable and a factor or a combination of factors in a repeated measure design. So I use lme() function in R. However, I am getting very different results depending on whether I add on the lme formula various factors

Re: [R] Differences in output of lme() when introducing interactions

2015-07-20 Thread Michael Dewey
In-line On 20/07/2015 15:10, angelo.arc...@virgilio.it wrote: Dear List Members, I am searching for correlations between a dependent variable and a factor or a combination of factors in a repeated measure design. So I use lme() function in R. However, I am getting very different results