[R] Reproducibility of experiment

darteta001 at ikasle.ehu.es darteta001 at ikasle.ehu.es
Mon Dec 17 16:27:52 CET 2007

Dear Marc and R-list,

thanks for your help. I 
have checked Bland-Altman help 
page about repeatability, and I learnt that instead of 
I was talking about repeatability. Although I am not sure whether they 
focuse on agreement of two different measurement methods, and not 
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 
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


> On Wed, 2007-12-12 at 17:23 +0100, darteta001 at ikasle.ehu.es wrote:
> > Dear list,
> > 
> > I have an experiment that I have run 10 times in order to find out 
> > reproducibility. I wonder if there is any function that I can use 
> > obtaining a significance value of reproducibility or agreement of 
> > measurements. I thought of coefficient of variation but, as far as 
> > know, I would have to set a threshold for saying the experiment is 
> > reproducible. Any pointers to something more "objective" would be 
> > helpful.
> > 
> > Thanks
> > 
> > David
> I suspect that you are going to have to be more specific regarding 
> 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 
> 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

More information about the R-help mailing list