Re: Inferential stats on TI-89: Pool the lists?
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Re: Inferential stats on TI-89: Pool the lists?
Thanks for your quick response! You are probably right. I have one more
question, though. I just noticed that my TI-89 asks me whether to pool the
lists when either data input method is used. Does it make sense to pool the
lists when stats are used?
It is of course quite possible that this is a bug in the program - or
perhaps a common SD can be calculated on the basis of the statistics?
Yours,
Haakon Hansen,
Norway
-----Original Message-----
From: Discussion of TI Graphing Calculators in Education
[mailto:GRAPH-TI@LISTS.PPP.TI.COM]On Behalf Of Nester, Darryl
Sent: Saturday, November 27, 1999 3:16 PM
To: GRAPH-TI@LISTS.PPP.TI.COM
Subject: Re: Inferential stats on TI-89: Pool the lists?
> I have the Inferential Statistics Package (infstat.89g) installed in my
> TI-89.
>
> The 2 Sample T Test (data input method: stats) requires an answer to the
> question 'Pool the lists?' Can anyone explain what this is about?
I assume that this is asking whether or not to assume that the standard
deviations of the two populations are equal. If we assume that they are
equal, we can "pool" the data from our two samples to come up with a
"pooled" estimate of the common standard deviation.
Opinion: Answer "no". This approach made sense before there was sufficient
computing power to handle the additional computations required for the
unequal SD case, but in reality, there is rarely good reason to assume that
SDs are equal.
--
Darryl K. Nester e-mail: mailto:nesterd@bluffton.edu
Assoc. Prof. of Mathematics WWW: http://www.bluffton.edu/~nesterd
Bluffton College phone: 419-358-3483 (w) 419-358-9650 (h)
Bluffton, OH 45817-1704 fax: 419-358-3232 (w) 419-781-7113 (h)
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