[R] accuracy of measurements

[Marc Schwartz]

On Feb 24, 2011, at 4:50 PM, Denis Kazakiewicz wrote:

> Dear R people
> Could you please help with following
> 
> Trying to compare accuracy of tumor size evaluation by different
> methods. So data looks like
> 
> id true metod1 method2 ... 
> 1  2	2	2.5
> 2  1.5	2	2
> 3  2	2	2
> 
> etc.
> 
> Could you please give a hint how to deal with that.
> Seems like {merror} does not suite to me because I am trying to compare
> accuracy of measurements with their true known values not just overall
> agreement of methods.
> Moreover sample size is ridiculously small (33 patients) so ANOVA is not
> much of help (or is it?)
> Any suggestions, hints and even guesses are highly appreciated. I am
> stuck a bit.


Denis,

I would suggest that you start here:

  http://www-users.york.ac.uk/~mb55/meas/meas.htm

This covers various resources pertaining to the design and analysis of measurement studies, primarily based upon methods by Bland and Altman.

HTH,

Marc Schwartz