Yes thank you very much! I knew i had different data points for each subject
per condition but didn't realise that it would affect the averages of the
averages!

Thank you for helping me solve this big headache of mine for the past 2 days
=)

Regards,
Ruijie (RJ)

--------
He who has a why can endure any how.

~ Friedrich Nietzsche


On 25 May 2010 01:50, jim holtman <jholtman@gmail.com> wrote:

> Notice that only column 19 in your original had the same for the
> average of the average and every entry had 32 data points.
>
> On Mon, May 24, 2010 at 1:47 PM, jim holtman <jholtman@gmail.com> wrote:
> > A quick check of you data shows that there are not the same number of
> > sample in each of the different conditions, therefore trying to take
> > the average of the averages will not work.
> >
> >      1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23
> 24
> >  1  32 31 29 30 24 23 31 32 32 31 24 23 29 24 30 26 20 17 32 32 32 31 24
> 23
> >  2  32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 31 24
> 24
> >  3  32 32 32 32 24 23 32 32 32 31 24 23 32 32 32 31 24 24 32 31 32 32 24
> 24
> >  4  31 29 31 29 22 21 31 28 31 29 24 23 29 29 30 26 22 24 32 31 31 30 20
> 24
> >  5  31 32 32 32 24 24 32 31 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  6  32 31 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 23
> 24
> >  7  32 31 32 31 24 24 32 32 32 32 24 24 32 32 32 32 23 24 32 32 32 32 24
> 24
> >  11 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  12 32 32 32 32 24 24 32 32 31 32 24 24 31 32 32 32 23 23 32 32 32 32 24
> 24
> >  13 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  14 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  15 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  16 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 31 23 23 32 32 32 31 24
> 24
> >  17 32 32 32 31 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  18 32 32 32 32 24 24 32 32 32 32 23 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  19 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  20 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  21 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24 24 32 32 32 32 24
> 24
> >  22 32 32 32 32 24 24 32 32 31 32 24 24 32 31 32 32 24 24 32 32 32 32 24
> 24
> >  23 32 32 32 32 24 24 32 32 32 31 24 23 32 32 32 31 24 24 32 32 32 32 24
> 24
> >
> >
> > On Mon, May 24, 2010 at 1:29 PM, Ruijie <breakaway8@gmail.com> wrote:
> >> Thanks for your help jim. I have attached the raw data to see if anyone
> else
> >> can replicate my problem.
> >>
> >> Correction: i realise my attachment was too large, I have uploaded it to
> >> another site. The link is:
> >> http://dl.dropbox.com/u/1443460/List%20-%20Raw%20Data.csv
> >>
> >>
> >> Regards,
> >> Ruijie (RJ)
> >>
> >> --------
> >> He who has a why can endure any how.
> >>
> >> ~ Friedrich Nietzsche
> >>
> >>>
> >>>
> >>> On 25 May 2010 00:17, jim holtman <jholtman@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 <breakaway8@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 <jholtman@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 <breakaway8@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?
> >>>>
> >>>
> >>>
> >>
> >>        [[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?
>

	[[alternative HTML version deleted]]

