Noted. I have attached a list of some data in csv format.
The first column is the SubID and the rest of the column are the mean of each condition for the particular subject. Average 1 is the average computed from each column in the list. Average 2 is computed from the raw data of all the data points of a condition. The difference is typically at the 3rd decimal place. If anyone needs the raw data, I could supply it after some clean up. I suspected round of errors but in all procedures in R, I retained 14 significant figures. How would the round off error affect the 3rd decimal place? Any ideas anyone? Regards, Ruijie (RJ) -------- He who has a why can endure any how. ~ Friedrich Nietzsche On 24 May 2010 22:47, jim holtman <jholt...@gmail.com> wrote: > It is hard to tell what you are doing without data and the results you > have gotten so far: > > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > > > On Mon, May 24, 2010 at 10:35 AM, Ruijie <breakaw...@gmail.com> wrote: > > Hi all, > > > > here is my situation > > > > In my experiment, I expose 10 subjects to 24 different conditions of > > stimuli. Each condition is exposed to the same subject 3x. > > This would make each subject have 24x3=72 data points. All the subjects > > combined would have 72x10=720 data points with each condition having 30 > > datapoints. > > > > To find the grand average of each condition, I find the average of all > the > > datapoints for a given condition. > > > > To find the SD for each condition, if I use the raw dataset (720 > datapoints) > > it would not reflect the SD across subjects. Therefore, I compute the > > average for each condition per subject .i.e. For subject 1, I would find > the > > average of condition 1 (average across 3 trials). and so on. > > With the average of each condition per subject, I then compute the SD. > > > > Since I computed the average of each condition per subject, > theoretically, > > if i average the average of each condition per subject across all > subjects, > > the result would be the same as the grand average. > > > > However, this is not the case when I use R or Excel. regardless of > functions > > used. Anyone have any thoughts? > > > > Regards, > > Ruijie (RJ) > > > > -------- > > He who has a why can endure any how. > > > > ~ Friedrich Nietzsche > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > 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. > > > > > > -- > Jim Holtman > Cincinnati, OH > +1 513 646 9390 > > What is the problem that you are trying to solve? >
______________________________________________ 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.
