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#1 2013-10-18 09:26:30

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,552

Mean, Median and Mode from Grouped Frequencies

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

All feedback welcome!


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

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#2 2013-10-18 12:01:26

bobbym
Administrator
From: Bumpkinland
Registered: 2009-04-12
Posts: 90,672

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!


In mathematics, you don't understand things. You just get used to them.

I agree with you regarding the satisfaction and importance of actually computing some numbers. I can't tell you how often I see time and money wasted because someone didn't bother to run the numbers.

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#3 2013-10-18 22:28:49

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,532

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


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#4 2013-10-21 16:17:14

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,552

Re: Mean, Median and Mode from Grouped Frequencies

Very interesting, thanks!


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

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