At 12:31 PM 8/27/01 +0000, EugeneGall wrote:
> The Harcourt-Brace description of the boxplot, which is now being taught
>to MA students, isn't a proper boxplot (maybe the Harcourt-Brace K-12 boxplot
>is different from the Tukey boxplot), becuase it doesn't properly plot
>outliers
>and extreme outliers.
of course, boxplots do NOT have to show outliers if there are none,
correct? so, what you are saying is that in THIS case ... since you have
done more digging into the boxplot put on item 39 ... and have concluded
that it is not properly designated ... that it is wrong
now, i made a data set ... here is the old time boxplot ... that you can
get from minitab ... which is perfectly legit ...
Boxplot
---------------------
--------------------I + I----------
---------------------
----+---------+---------+---------+---------+---------+--C1
20.0 22.0 24.0 26.0 28.0 30.0
there is no designation for outliers since, by definition in this data set
... there are none
in the better graphic version minitab has ... all you see are single lines
extending from the hinges ... with NO other symbols (dots, etc.)
thus, in the item 39 example ... while i assume that the dots at both ends
are just meant to show where the data stop ... this is not how (i dare
say?) ANY software would show it ...
however, if the boxplot were done by hand ... you might see the texts that
they are using depict it this way ... draw a box ... extend lines ... put
dots at the end to signify more clearly ... the ends ... and the notion of
"outliers" MAY NOT enter into the discussions carried on in mass. class
curricula ...
in any case ... we have a messy item ... by ANY criterion used
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_________________________________________________________
dennis roberts, educational psychology, penn state university
208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED]
http://roberts.ed.psu.edu/users/droberts/drober~1.htm
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