[R-sig-ME] specifying model with multiple interactions

[Ista Zahn]

Hi James,
I think you probably want something along the lines of

 BatUp ~ Speed + Delivery + (1|Subject) + (0+Speed|Subject) +
(0+Delivery|Subject)

assuming that Subject is a unique identifier for each participant. I
highly doubt that you want the (1|Delivery) term in there, as it
surely makes more sense to think of this as a fixed factor.

I'm sure someone will correct me if I'm wrong...
-Ista

On Mon, Mar 1, 2010 at 5:47 PM, James Croft <james.croft at aut.ac.nz> wrote:
> I am having trouble specifying a mixed effects model and would appreciate
> some guidance.
>
> Background
> We are interested in how cricket batsmen respond to balls delivered from
> bowling machines. We filmed batsmen facing deliveries at different speeds
> from a bower and machine. The data is very expensive because each video has
> to be digitized by hand to identify various parameters of interest. Hence we
> only have data on 13 subjects (and it has missing values).
>
> One objective is to predict the timing of bat lift (BatUp) by delivery speed
> (Speed) for a given condition (Delivery) and to assess the variability
> across subjects (Subject).
>
> Delivery  : Factor w/ 2 levels "Bowler","Machine"
> Subject   : Factor w/ 13 levels
> Speed     : num
> BatUp     : num
>
> So I believe I want to predict a fixed effect for speed and random slope and
> intercept for each level of a factor created by Subject:Delivery
>
> I'm getting a bit confused with the combinations of random effect.
> I have read through a few of the chapters  of Doug Bates. (2010). lme4:
> Mixed-effects modeling with R.
>
> This is as far as I have got...
>
> BatUp ~ Speed + (1|Delivery) + (1|Subject) + (1|Subject:Delivery) +
> (0+Speed|Subject:Delivery)
>
> Thanks in advance for any help.
>
> Regards,
> James
>
>
>
>
>
>
>
>
>
> Regards,
> James
>
>
> ________________________________________
> James Croft, PhD
> Research Fellow
> Sport Performance Research Institute New Zealand
> School of Sport and Recreation
> AUT University
> Private Bag 92006
> Auckland 1142
> New Zealand
>
> Phone 64-9-921 9999 ext 7685
> Fax 64-9 921 9960
> Email james.croft at aut.ac.nz
> http://www.isrrnz.ac.nz/
>
> _______________________________________________
> R-sig-mixed-models at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-sig-mixed-models
>



-- 
Ista Zahn
Graduate student
University of Rochester
Department of Clinical and Social Psychology
http://yourpsyche.org