[R] Simple mean trajectory (ordinal variable)

[David Winsemius]

On Jun 29, 2012, at 9:29 AM, Frank Harrell wrote:

> David - I didn't see a fun= argument to panel.loess
> Frank

I imagine that argument was just being thrown away. I wasn't paying  
any attention for the request for plotting means ... only addressing  
the request to get rid of the points.

I suppose one could have used panel.xyplot to plot the means, but the  
OP did not include a sample dataset, and I have gotten rather  
selective about what sorts of datasets I will build on the fly when  
posters fail to supply them.

-- 
David.

>
> David Winsemius wrote
>>
>> 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
>>>

David Winsemius, MD
West Hartford, CT