RE: st: Repeated measured analysis

[Marlis Gonzalez Fernandez <mgonzal5@jhmi.edu>]

Thank you Ronán-

I agree looking not only at food but the interaction between food and disease will be really intresting...

Thanks for the suggestions.

Marlis

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Ronan Conroy
Sent: Wednesday, August 10, 2011 12:15 PM
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: Repeated measured analysis

On 2011 Lún 10, at 16:44, Marlis Gonzalez Fernandez wrote:

> Hello-
> 
> Trying to help a colleague who has an interesting study.
> 
> He has distance of movement (hyoid bone) measures in mm on 13 subjects with no less than 20 measures (some have many more than that) during swallowing 3 different foods (so lots of repeats!). He wants to determine if there are significant distance differences between normal and disease states (while taking into account food type). I was concerned about having so many repeated measures and appropriately accounting for that to discern where is the true variability (ie. disease state?  Subject?).  Any ideas welcome.maybe I am over-thinking this?  Should he just analyze food types separately?

Why not -svyset- with participant as the PSU? 

The interesting question was whether food type interacted with disease status. In achalasia, difficulty swallowing varies considerably by food type, and this may be true for other disorders of swallowing too - it's not my area - but I'd have a look at the interaction term.


Ronán Conroy
rconroy@rcsi.ie
Associate Professor
Division of Population Health Sciences
Royal College of Surgeons in Ireland
Beaux Lane House
Dublin 2


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