median standard deviation

[Omics]

Hi, Anybody can tell me which function or formula should I use in excel to
calculate the median standard deviation? Thanks a lot.

Omics

 

[Luke M]

That is two seperate statistical functions!

Median:
=MEDIAN(...)

Standard Deviation:
=STDEV(...)

Check out the help file on statistical functions for more details.

 

[dlw]

let's say your standard deviations were in cells a1 to a5, the median would be:
=median(a1:a5)

 

[Omics]

Thanks, a lot. This will give me the median of the data. But how can I
calculate the median standard deviation?

Omics

 

[Joe User]

Hi, Anybody can tell me which function or formula
should I use in excel to calculate the median
standard deviation?

You will need to be more careful with your terminology if you want a
meaningful answer.

First, are you referring to the median or the mean (arithmetic average)?

The median is the middle value of the data. The mean is the average of the
data. For example, if the data are 1, 4 and 5, 4 is the median, whereas the
mean is about 3.33.

Note that the standard deviation (emphasis on "standard") is defined as a
deviation from the mean, not the median.

I 'spose that you could substitute the median for the mean in the standard
deviation formula. (See the STDEVP help page.) But then it would not be
"standard" ;-). And the usefulness of such a measure is unclear.

On the other hand, the median deviation is defined as the average of the
absolute deviations from the median.

To my knowledge, there is no Excel formula for that. You can compute it
with the following array formula [*]:

=SUM(ABS(A2:A100-A1:A99))/100

[*] Enter an array formula by pressing ctrl+shift+Enter instead of just
Enter. In the Formula Bar, you will see curly braces around the entire
formula, viz. {=formula}. You cannot type the curly braces yourself; that is
just Excel's way of denoting an array formula. If you make a mistake, select
the cell, press F2, edit as needed, then press ctrl+shift-Enter.

Lastly, if you mean that you have a set of standard deviations, and you want
to calculate their median, you could use =MEDIAN(A1:A10). But again, the
usefulness of such a measure is unclear.

 

[Joe User]

This will give me the median of the data.

Not really. It computes the median of a set of standard deviations. In
other words, the data are a set of standard deviations.

If that does not make much sense to you, don't worry. I see little use for
it myself.

Judging from your response, it is not applicable to you.


----- original message -----

 

[dlw]

If you are doing a homework assignment which is asking to calculate the
"median standard deviation" it is in fact a trick question, because there is
no such thing. My statistics professor was always pulling stunts like
that... Like asking us to calculate the "3rd order angular mean" or the
"compressed flux regression test" etc...

 

[Joe User]

Errata....

the median deviation is defined as the average of the absolute deviations
from the median. [....] You can compute it with the following array
formula [*]:
=SUM(ABS(A2:A100-A1:A99))/100

Brain fart! I mean:

=SUM(ABS(A1:A100-MEDIAN(A1:A100)))/100

And note that for "/100", 100 relates to the number of data points (100),
not a constant like "percent".


----- original message -----

Hi, Anybody can tell me which function or formula
should I use in excel to calculate the median
standard deviation?

You will need to be more careful with your terminology if you want a
meaningful answer.

First, are you referring to the median or the mean (arithmetic average)?

The median is the middle value of the data. The mean is the average of
the
data. For example, if the data are 1, 4 and 5, 4 is the median, whereas
the
mean is about 3.33.

Note that the standard deviation (emphasis on "standard") is defined as a
deviation from the mean, not the median.

I 'spose that you could substitute the median for the mean in the standard
deviation formula. (See the STDEVP help page.) But then it would not be
"standard" ;-). And the usefulness of such a measure is unclear.

On the other hand, the median deviation is defined as the average of the
absolute deviations from the median.

To my knowledge, there is no Excel formula for that. You can compute it
with the following array formula [*]:

=SUM(ABS(A2:A100-A1:A99))/100

[*] Enter an array formula by pressing ctrl+shift+Enter instead of just
Enter. In the Formula Bar, you will see curly braces around the entire
formula, viz. {=formula}. You cannot type the curly braces yourself; that
is
just Excel's way of denoting an array formula. If you make a mistake,
select
the cell, press F2, edit as needed, then press ctrl+shift-Enter.

Lastly, if you mean that you have a set of standard deviations, and you
want
to calculate their median, you could use =MEDIAN(A1:A10). But again, the
usefulness of such a measure is unclear.