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Science Forum Index » Statistics - Education Forum » method to find two groups in population...
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| Alex Lee... |
 Posted: Wed May 07, 2008 11:59 am |
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Dear all:
Is there a way that I can find (mine) two groups in a given
population. An example would be something like this:
women drinks 2x more water than men.
A study was conducted and a set of data was given as such.
person 1: 1 liter
person 2: 1.2 liter
person 3: 500 ml
person 4: 2 liter
person 5: 200 ml
person 6: 700 ml
A computer mining program will then group
person 1,2,4 as group A
person 3, 5, 6 as group B
Is this possible?
thank you.
Alex  |
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| Richard Ulrich... |
| Posted: Thu May 08, 2008 6:10 pm |
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On Wed, 7 May 2008 14:59:36 -0700 (PDT), Alex Lee
<simplitia at (no spam) gmail.com> wrote:
Quote: Dear all:
Is there a way that I can find (mine) two groups in a given
population. An example would be something like this:
women drinks 2x more water than men.
A study was conducted and a set of data was given as such.
person 1: 1 liter
person 2: 1.2 liter
person 3: 500 ml
person 4: 2 liter
person 5: 200 ml
person 6: 700 ml
A computer mining program will then group
person 1,2,4 as group A
person 3, 5, 6 as group B
Is this possible?
Sort them in order. Draw a line.
If you want, you can evaluate a statistic that measures
the distance achieved between groups.
--
Rich Ulrich
http://www.pitt.edu/~wpilib/index.html |
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| JoJo... |
| Posted: Fri May 09, 2008 1:39 pm |
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Richard Ulrich wrote:
Quote: On Wed, 7 May 2008 14:59:36 -0700 (PDT), Alex Lee
[..]
Is there a way that I can find (mine) two groups in a given
population.
[..]
Sort them in order. Draw a line.
Ah, so simple. But where exactly?
For example, why draw a line between sorted third and fourth and not 2nd
and 3rd?
Quote: If you want, you can evaluate a statistic that measures
the distance achieved between groups.
Maybe we should try to minimize something ?
What? Sum of (inter-cluster) variances ?
What if the data are: 500ml, 700ml, 1L, 1.2L, 1.8L, 2.1L ?
This looks more like three groups, not two.
Alex,
If we know that there are exactly TWO groups, why don't we know who
belongs to which group? Lost the labels? The example is somewhat
unconvincing, you can surely distinguish men and women using other means
with no need to check their drinking habits.
JoJO |
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