Thanks for your help jim. I have attached the raw data to see if anyone else can replicate my problem.
Regards, Ruijie (RJ) -------- He who has a why can endure any how. ~ Friedrich Nietzsche On 25 May 2010 00:17, jim holtman <jholt...@gmail.com> wrote: > Are you sure that you have the same number of data points in each of > the summary cells that you show in your csv file that was sent? You > need to provide a reproducible example of all the data so we can see > what you did. The best information I can provide at this point is > that you have a "bug" in your calculations. > > On Mon, May 24, 2010 at 11:10 AM, Ruijie <breakaw...@gmail.com> wrote: > > 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? > > > > > > > > -- > 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.
