[R] Summary vs fivenum results for Q3

[Schaefer, Robert L. Dr.]

I've just started using R and am still a neophyte, but I found the following curious result.  I'm using the current version of R (2.5.1 (2007-06-27) ).

Why are the results for the third quartile different in the output from the summary and fivenum commands?  For the following data set

457     514     530     530     538     560     687     745     745     778     786     790     792     821     821     822     822
828     845     850     886     886     886     913     1050    1050    1065    1065    1065    1065    1090    1130

Summary yields:

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max.
  457.0   745.0   822.0   825.4   947.2  1130.0

While fivenum yields:

[1]  457.0  745.0  822.0  981.5 1130.0

The third quartile is being correctly calculated in the fivenum command and incorrectly in the summary command.

Bob

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Robert L. Schaefer, Professor of Statistics
Department of Mathematics and Statistics
Miami University
Oxford, Ohio 45056  (513) 529-3533 (513) 529-5818 (sec)
SchaefRL at MUOhio.Edu  HTTP://WWW.USERS.MUOHIO.EDU/SchaefRL
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