Re: [R] question in using nlme and lme4 for unbalanced data

2010-11-02 Thread Mike Marchywka
> Date: Mon, 1 Nov 2010 17:38:54 -0700 > From: djmu...@gmail.com > To: cy...@email.arizona.edu > CC: r-help@r-project.org > Subject: Re: [R] question in using nlme and lme4 for unbalanced data > > Hi: > > On Mon, Nov 1

Re: [R] question in using nlme and lme4 for unbalanced data

2010-11-01 Thread Ben Bolker
Chi Yuan email.arizona.edu> writes > > Hello: > I need some help about using mixed for model for unbalanced data. I > have an two factorial random block design. It's a ecology > experiment. My two factors are, guild removal and enfa removal. Both > are two levels, 0 (no removal), 1 (removal). I

Re: [R] question in using nlme and lme4 for unbalanced data

2010-11-01 Thread Dennis Murphy
Hi: On Mon, Nov 1, 2010 at 3:59 PM, Chi Yuan wrote: > Hello: > I need some help about using mixed for model for unbalanced data. I > have an two factorial random block design. It's a ecology > experiment. My two factors are, guild removal and enfa removal. Both > are two levels, 0 (no removal),

[R] question in using nlme and lme4 for unbalanced data

2010-11-01 Thread Chi Yuan
Hello: I need some help about using mixed for model for unbalanced data. I have an two factorial random block design. It's a ecology experiment. My two factors are, guild removal and enfa removal. Both are two levels, 0 (no removal), 1 (removal). I have 5 blocks. But within each block, it's unbala

Re: [R] question in using nlme and lme4 for unbalanced data

2010-10-25 Thread Ben Bolker
On 10-10-25 04:59 PM, Bert Gunter wrote: > ...ignore the block variation entirely, " > > If the between block variability is large, this will lose precision; > with imbalance, it could also result in bias (prhaps not in this > study...). The mixed or fixed effects choice is arbitrary; this is not

Re: [R] question in using nlme and lme4 for unbalanced data

2010-10-25 Thread Ben Bolker
Bert Gunter gene.com> writes: Thanks for starting this. I don't really disagree, much. > I would say that these are not really R questions, but about > statistical procedures in general. However, there are some important > issues that you touch on, so I cannot resist commenting. Hopefully my

Re: [R] question in using nlme and lme4 for unbalanced data

2010-10-25 Thread Bert Gunter
Chi: I would say that these are not really R questions, but about statistical procedures in general. However, there are some important issues that you touch on, so I cannot resist commenting. Hopefully my comments might pique others to add theirs -- and perhaps to disagree with me. 1. Unbalanced

[R] question in using nlme and lme4 for unbalanced data

2010-10-25 Thread Chi Yuan
Hello: I have an two factorial random block design. It's a ecology experiment. My two factors are, guild removal and enfa removal. Both are two levels, 0 (no removal), 1 (removal). I have 5 blocks. But within each block, it's unbalanced at plot level because I have 5 plots instead of 4 in each blo