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Re: Mean


You've apparently used Mean without (or before) loading the package
that contains it. It's in the System context in 5.0.1, but in earlier
versions, you have to load a package such as
Statistics`DescriptiveStatistics`. Look up Mean in Help, and you can
find out which package to load, and how. Something like...

<<Statistics`DescriptiveStatistics`

or

Needs["Statistics`"]

The latter is simplest, especially if you put it in your Init.m file.
It means you never have to manually load a Statistics package.

Bobby

per.ronne at doesnt.work.spam.filter.invalid wrote in message news:<c81hen$4sd$1 at smc.vnet.net>...
> I've just purchased Mathematica 5 but I've got some problems.
> 
> I write:
> 
> boys = 
>   {192, 176, 178, 180, 189, 173, 177, 176, 176, 194,
>     178, 172, 175, 180, 170, 174, 180, 184, 177, 181,
>     190, 186, 187, 184, 190, 180, 178, 182, 181, 180,
>     175, 182, 182, 181, 179, 190, 173, 189, 173, 183,
>     172, 178, 182, 172, 190, 180, 176, 177, 181, 185,
>     174, 178, 178, 178, 170, 175, 178, 186, 185, 182,
>     179, 187, 183, 188, 191, 180, 193, 183, 185, 174,
>     174, 180, 191, 180, 177, 185, 192, 187, 170, 176,
>     170, 184, 179, 173, 184, 184, 190, 179}
> 
> But when I try to get their average height [it is the height of boys in
> Danish upper grammar schools, grade 13 at the age of around 19], I get:
> 
> Mean[boys]
> Mean[{192, 176, 178, 180, 189, 173, 177, 176, 176, 194, 178, 172, 175,
> 180, 
>     170, 174, 180, 184, 177, 181, 190, 186, 187, 184, 190, 180, 178,
> 182, 181,
>      180, 175, 182, 182, 181, 179, 190, 173, 189, 173, 183, 172, 178,
> 182, 
>     172, 190, 180, 176, 177, 181, 185, 174, 178, 178, 178, 170, 175,
> 178, 186,
>      185, 182, 179, 187, 183, 188, 191, 180, 193, 183, 185, 174, 174,
> 180, 
>     191, 180, 177, 185, 192, 187, 170, 176, 170, 184, 179, 173, 184,
> 184, 190,
>      179}]
> 
> And it doesn't help to put on a //N:
> 
> Mean[boys] // N
> Mean[{192., 176., 178., 180., 189., 173., 177., 176., 176., 194., 178.,
> 172., 
>     175., 180., 170., 174., 180., 184., 177., 181., 190., 186., 187.,
> 184., 
>     190., 180., 178., 182., 181., 180., 175., 182., 182., 181., 179.,
> 190., 
>     173., 189., 173., 183., 172., 178., 182., 172., 190., 180., 176.,
> 177., 
>     181., 185., 174., 178., 178., 178., 170., 175., 178., 186., 185.,
> 182., 
>     179., 187., 183., 188., 191., 180., 193., 183., 185., 174., 174.,
> 180., 
>     191., 180., 177., 185., 192., 187., 170., 176., 170., 184., 179.,
> 173., 
>     184., 184., 190., 179.}]
> 
> If I look up in the Stephen Wolfram's Mathematica book 5th Edition on
> page 109, it should be possible to get:
> 
> data = {4.7, 7.2, 8.4, 5.8, 9.2, 3.9}
> Mean[data]
> 6.46667
> 
> But instead I get:
> 
> Mean[{4.7, 7.2, 8.4, 5.8, 9.2, 3.9}]
> 
> What is wrong?


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