[R] Simple mean trajectory (ordinal variable)

[David Winsemius]

On Jun 28, 2012, at 1:50 PM, Eiko Fried wrote:

> Hello.
>
> I have 5 measurement points, my dependent variable is ordinal (0 -  
> 3), and
> I want to visualize my data. I'm pretty new to R.
> What I want is to find out whether people with different baseline
> covariates have different trajectories, so I want a plot with the  
> means
> trajectory of my dependent variable (the individual points do not  
> make a
> lot of sense in ordinal data) on each measurement point per group,  
> e.g.
> females vs. males.
>
> I found different codes, but they don't work well for me. This one  
> looks
> promising, though:
>
>> xyplot(phq4 ~ time, data = data, type = 'l',
>>      panel=function(...){
>>        panel.xyplot(...)

If you do not want to plot the points then you should drop the call to  
xyplot(...)

>>        panel.loess(...,fun=mean,horizontal=FALSE,col='red',lwd=3)
>>      }
>>      )
>
> Works and gives me the mean trajectory (I think), but also the  
> individual
> trajectories (so I'd like to get rid of them). Also, I would need a  
> way to
> build 2 trajectories in 2 graphs ("group=gender" only gives 1 mean
> trajectory), + standard deviations or something similar that makes  
> sense as
> a measure of variance.
>
> Thanks
> -T
>
> 	[[alternative HTML version deleted]]
>
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David Winsemius, MD
West Hartford, CT