[R] [Newbie] Is there any support for work with grouped frequencies?

[Yves Brostaux]

For the mean, there is a function called weighted.mean() and you can use it 
as a start for custom functions.

An alternative is to expand your grouped data before applying your 
function, e.a.

 > x <- rep(wtc$MIDPOINT, wtc$FREQ)
 > c(Mean=mean(x), Var=var(x))

but it isn't appropriate for some parameters (it doesn't give interpolated 
median, etc)

At 04:01 14/11/02, you wrote:
>Date: Wed, 13 Nov 2002 10:04:00 -0500
>From: Matej Cepl <matej at ceplovi.cz>
>Subject: [R] [Newbie] Is there any support for work with grouped frequencies?
>
>Hi,
>
>I have this table (BTW, published by FBI and representing age
>distribution of the WTC tragedy victims):
>
>         "LABEL" "FREQ" "MIDPOINT"
>         "1" "Infant (under 1)"   0
>         "2" "1 to 4"   5
>         "3" "5 to 8"   1
>         "4" "9 to 12"   3
>         "5" "13 to 16"   0
>         "6" "17 to 19"   3
>         "7" "20 to 24" 117
>         "8" "25 to 29" 341
>         "9" "30 to 34" 503
>         "10" "35 to 39" 578
>         "11" "40 to 44" 510
>         "12" "45 to 49" 369
>         "13" "50 to 54" 272
>         "14" "55 to 59" 177
>         "15" "60 to 64"  79
>         "16" "65 to 69"  29
>         "17" "70 to 74"  15
>         "18" "75 and over"  11
>         "19" "Unknown" NA
>
>Are there any tools to work with grouped frequencies (i.e.,
>median, mean, chi-square test of normality of distribution) or do
>I have to calculate them ``by hand''?
>
>Thanks for any answer,
>
>         Matej
>
>- --
>Matej Cepl, matej at ceplovi.cz,
>Finger: 89EF 4BC6 288A BF43 1BAB  25C3 E09F EF25 D964 84AC
>138 Highland Ave. #10, Somerville, Ma 02143, (617) 623-1488
>
>The ratio of literacy to illiteracy is a constant, but nowadays
>the illiterates can read.
>     -- Alberto Moravia

-- 
Ir. Yves Brostaux - Statistics and Computer Science Dpt.
Gembloux Agricultural University
8, avenue de la Faculté B-5030 Gembloux (Belgium)
Tél : +32 (0)81 62 24 69
E-mail : brostaux.y at fsagx.ac.be
Web : http://www.fsagx.ac.be/si/


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