[Rd] Accuracy in summary (PR#7121)

[murdoch at stats.uwo.ca]

On Tue, 20 Jul 2004 15:54:49 +0200 (CEST), sandy at stat.umn.edu wrote :

>Full_Name: Sanford Weisberg
>Version: 1.9.1
>OS: Win XP
>Submission from: (NULL) (160.94.148.2)
>
>
>> wm <- read.table(url("http://www.stat.umn.edu/~sandy/wmdata0.txt"),
>header=TRUE)
>> mean(wm$Spd1)
>[1] 7.7773
>> summary(wm$Spd1)
>   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
>  0.222   4.780   7.550   7.780  10.200  21.600 
>
>The mean of this variable DOES NOT ROUND to the value shown in the summary
>output. 

This is not a bug. summary.default() is behaving as documented.  You
asked (by default) for 3 significant figures, and that's what you got.

>
>> options(digits=6)
>> mean(wm$Spd1)
>[1] 7.77733
>> summary(wm$Spd1)
>   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
>  0.222   4.780   7.550   7.780  10.200  21.600
>
>This is still wrong.  Also, the minimum value is 0.2221, which should have been
>printed in full given digits=6.

No, see the man page.

Duncan Murdoch