[R] Extrapolating data points for individuals who lack them

Mike Marchywka marchywka at hotmail.com
Wed Apr 20 16:38:06 CEST 2011

> From: de223 at exeter.ac.uk
> To: r-help at r-project.org
> Date: Wed, 20 Apr 2011 12:41:29 +0100
> Subject: [R] Extrapolating data points for individuals who lack them
> Hi,
> We have an experiment where individuals responses were measured over 5 days. Some responses were not obtained because we only allowed individuals to respond within a limited time-frame. These individuals are given the maximum response time as they did not respond, yet we feel they may have done if given time (and by looking at the rest of their responses over time, the non-response days stand out).
> We therefore want to extrapolate data points for individuals, on days when they didn't respond, using a regression of days when they did.
> Does anyone know how we could do this quickly and easily in R?

You are probably talking about right censoring. See things like this, 
( you may have good luck just with "R" rather than "CRAN" ) 


If you post data maybe someone can try a few things. It isn't hard to take data
subsets, fit models, and replace data with model predictions but easier and more
interesting to illustrate with your data.

Personally I would avoid making up data and of course extrapolation tends
to be the most error prone way of doing that. 

> Thanks very much
> Dave


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