Means do not tally

classic Classic list List threaded Threaded
9 messages Options
Reply | Threaded
Open this post in threaded view
|

Means do not tally

Ruijie
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]]

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

Ben Bolker
Ruijie <breakaway8 <at> gmail.com> writes:

> 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.

 [snip]

> 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?

  Nothing obvious springs to mind. We need a reproducible example.
How different are the means computed in different ways?  Is the
difference attributable to round-off error?

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

Ruijie
In reply to this post by Ruijie
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 <[hidden email]> 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 <[hidden email]> 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]]
> >
> > ______________________________________________
> > [hidden email] 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?
>

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

jholtman
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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]]
>> >
>> > ______________________________________________
>> > [hidden email] 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?

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

Ruijie
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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]]
> >> >
> >> > ______________________________________________
> >> > [hidden email] 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?
>

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

Ruijie
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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]]
>> >> >
>> >> > ______________________________________________
>> >> > [hidden email] 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]]

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

jholtman
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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]]
>>> >> >
>>> >> > ______________________________________________
>>> >> > [hidden email] 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]]
>
> ______________________________________________
> [hidden email] 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?

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

jholtman
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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]]
>>>> >> >
>>>> >> > ______________________________________________
>>>> >> > [hidden email] 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]]
>>
>> ______________________________________________
>> [hidden email] 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?

______________________________________________
[hidden email] 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.
Reply | Threaded
Open this post in threaded view
|

Re: Means do not tally

Ruijie
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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]> 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 <[hidden email]>
> 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 <[hidden email]> 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 <[hidden email]>
> 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]]
> >>>> >> >
> >>>> >> > ______________________________________________
> >>>> >> > [hidden email] 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]]
> >>
> >> ______________________________________________
> >> [hidden email] 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]]

______________________________________________
[hidden email] 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.