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MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Mean, Median and Mode from Grouped Frequencies

Another new stats page: Mean, Median and Mode from Grouped Frequencies

All feedback welcome!

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Mean, Median and Mode from Grouped Frequencies

Hi;

That was a lot more than I knew about it. I will use the page for notes, thanks!

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,621

Re: Mean, Median and Mode from Grouped Frequencies

hi MathsIsFun,

Another good page.  I'd not met those formulas for median and mode in grouped tables; I've always worked from a sketch of a cumulative frequency graph; so I derived my own.

For continuous data, taking the median as the (n+1)/2 th value I get

It doesn't make much difference and it's only an estimate anyway, but, for example, with the baby carrots example I get 172.0, compared with your 171.7.

I drew a cumulative frequency graph and found the median from that as 172.

I've done some 'googling' and both formulas came up.

eg.

http://www.thestudentroom.co.uk/showthread.php?t=908222

http://math.stackexchange.com/questions … stribution

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: Mean, Median and Mode from Grouped Frequencies

Very interesting, thanks!

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman