Re: How do I explain the concept of degrees of freedom?
- From: "Greg Heath" <heath@xxxxxxxxxxxxxxxx>
- Date: 10 Sep 2006 06:06:24 -0700
dave@xxxxxxxxxxx wrote:
Liesl wrote:
Hi everyone,
I'm a post-graduate psychology student who was recently trying (with
difficulty) to explain the concept of degrees of freedom to an
undegraduate student (in the context of t-tests).
I was wondering if someone could please offer me some advice on how to
best explain the concept of degrees of freedom (as they relate to
t-tests) in layman's terms.
Does anyone know of a website which offers diagrams (or better yet,
java applets) which demonstrate the concept of degrees of freedom
(i.e., how they relate to sample statistics and population parameters)?
Thanks,
Liesl
I have waited for someone smarter than I to explain this to you ....but
there have been no takers ..
Thus I veer from my domain of excellence .... time series analysis and
forecasting and put on my academic hat ...
If I have 5 observations and I compute and report to you the MEAN of
these 5 ....then any set of 4 taken from the 5 will be SUFFICIENT to
determine the missing value ... recall I gave you 4 of the 5 and
witheld 1 ...
Thus the 5 values GIVEN THE MEAN have 4 values that are free to vary
Now if I give you the MEAN and the STANDARD DEVIATION ...then any three
of the 5 will be suffucient for you to solve for the missing two ....
SAMPLE MEAN and SAMPLE STANDARD DEVIATION
Thus degrees of freedom means the number of values necessary to fully
descibe ( or list ) the complete set.
.... given the sample estimates.
Hope this helps.
Greg
.
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