Re: [R] analysing a three level reponse

2011-06-22 Thread Robert A LaBudde
The best method would probably be proportional odds regression using polyr() in 'MASS'. At least it's a starting point. At 09:19 AM 6/22/2011, Matt Ellis \(Research\) wrote: Hello, I am struggling to figure out how to analyse a dataset I have inherited (please note this was conducted some tim

Re: [R] analysing a three level reponse

2011-06-22 Thread David Cross
You could analyze these data with a multinomial logit model, with an ordinal response. I don't have my copy handy, but I know that Agresti (Categorical Data Analysis, Wiley) covers these models. Cheers David Cross d.cr...@tcu.edu www.davidcross.us On Jun 22, 2011, at 8:19 AM, Matt Ellis (R

[R] analysing a three level reponse

2011-06-22 Thread Matt Ellis (Research)
Hello, I am struggling to figure out how to analyse a dataset I have inherited (please note this was conducted some time ago, so the data is as it is, and I know it isn't perfect!). A brief description of the experiment follows: Pots of grass were grown in 1l pots of standad potting medium for 1