[R-sig-teaching] t.test from summary of data

[Robert W. Hayden]

Forwarded message:
> From: "Byungchul Cha" <cha at muhlenberg.edu>
 
> We use "Intro to the practice of statistics" by Moore, McCabe, Craig
  as textbook. Is there an option for the command "t.test" so that it
  can perform t-test from the summary of sample data (that is, sample
  mean, sample sd, and sample size), instead of the (raw) sample data?
  I've been looking to find a way to do so, but, I couldn't.  I
  believe it is possible to write codes to do this for my own use,
  but, I am just curious. Is there a pedagogical reason not to do so?

YES!

One of the reasons to use statistical software in a first course is so
that students can work with real, raw data.  For example, it is nearly
imnpossible to check assumptions if you do not have the data.
However, publishers want to sell books to EVERYONE, including those
who do not have or do not use any technology beyond a $2 calculator.
So the homework problems are driven by this least common denominator.  

These data-free homework problems provide practice in plugging numbers
into formulae, an Algebra I or even junior high school skill, and a
pretty minor skill for doing statistics in the real world.  So I would
suggest not assigning these and replacing them with problems that
involve real data, and asking students to LOOK AT THE DATA to check
assumptions and look for gross errors. I think you can find many real
data sets on the CD that comes with this text, and many are included
with R as well. Other sources include DASL and the _Journal of
Statitics Education_.

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