Dear Marc and R-list, thanks for your help. I have checked Bland-Altman help page about repeatability, and I learnt that instead of reproducibility, I was talking about repeatability. Although I am not sure whether they only focuse on agreement of two different measurement methods, and not on repeatability of one single method.
To explain further on my topic, I have repeated ten times an experiment involving protein quantification(i.e. how much protein I have), giving me ten continuous values. All experimental settings are similar so there should be no variability due to day of experiment, operator or any batch effect. My aim is to know whether these ten observations are good enough so that I can conclude that the repeatability of my detection technique is good. But as I have learnt from Altman´s page, it is not possible to set a threshold to the repeatability score to say my experiment is "repeatable". I guess I can obtain a 95% confidence interval for the protein quantification values, but I am not sure this will show how well my experiment performs. Putting it differently, something I would like to know is whether I can estimate beforehand how many times I need to run an experiment in order to be confident that it is "repeatable". Thanks for your comments David > > On Wed, 2007-12-12 at 17:23 +0100, [EMAIL PROTECTED] wrote: > > Dear list, > > > > I have an experiment that I have run 10 times in order to find out its > > reproducibility. I wonder if there is any function that I can use for > > obtaining a significance value of reproducibility or agreement of > > measurements. I thought of coefficient of variation but, as far as I > > know, I would have to set a threshold for saying the experiment is not > > reproducible. Any pointers to something more "objective" would be very > > helpful. > > > > Thanks > > > > David > > I suspect that you are going to have to be more specific regarding the > subject matter and the experimental design so that those with the > requisite expertise could comment. > > If this is looking at a continuous measure (ie. instrumentation > measurements), you could look at Bland-Altman methods. More information > here: > > http://www-users.york.ac.uk/~mb55/meas/meas.htm > > Otherwise, given that Google returns almost a million hits with the > phrase "reproducibility of experiment"... > > HTH, > > Marc Schwartz > > > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
