
Nov 15th, 2011, 06:01 AM
#1
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Nov 15th, 2011, 09:14 AM
#2
Re: how to calculate median of grouped data if group size is variable
Your formula remains valid for nonfixedwidth classes. h just needs to be the size of the class containing the median.
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Nov 16th, 2011, 02:37 AM
#3
Thread Starter
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Re: how to calculate median of grouped data if group size is variable

Nov 16th, 2011, 09:54 AM
#4
Re: how to calculate median of grouped data if group size is variable
There's some ambiguity in your description. Perhaps the best way to figure out which group the median lies in is probably to first add the frequencies to compute n (which you'll need to do anyway). Starting from the first group, successively add the group frequencies until you exceed n/2. The group which made you exceed n/2 contains the median.
Ex: given frequencies (in order) 5, 12, 3, 6, 9, 15, 25, we have n=75, so n/2 = 37.5. Successively adding frequencies from the left, we get 5, 5+12=17, 17+3=20, 20+6=26, 26+9=35, 35+15=50 > 37.5. Thus the median occurs in the second to last group, that of size 15.
The time you enjoy wasting is not wasted time.
Bertrand Russell
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Nov 18th, 2011, 12:33 AM
#5
Thread Starter
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Re: how to calculate median of grouped data if group size is variable
Originally Posted by jemidiah
There's some ambiguity in your description. Perhaps the best way to figure out which group the median lies in is probably to first add the frequencies to compute n (which you'll need to do anyway). Starting from the first group, successively add the group frequencies until you exceed n/2. The group which made you exceed n/2 contains the median.
Ex: given frequencies (in order) 5, 12, 3, 6, 9, 15, 25, we have n=75, so n/2 = 37.5. Successively adding frequencies from the left, we get 5, 5+12=17, 17+3=20, 20+6=26, 26+9=35, 35+15=50 > 37.5. Thus the median occurs in the second to last group, that of size 15.
Hello ,
I am using all the techniques requires to solve this and also what you have guided nut still i am not able to solve it till final solution.

Nov 18th, 2011, 01:01 AM
#6
Re: how to calculate median of grouped data if group size is variable
Ok.... Well, it should be quite obvious that the median occurs in the first group (which also follows from my median finding algorithm above). Then simply apply the formula L + (n/2cf)*h/f where...
L = 5, n = 715, cf = 0, h = 5, f = 500
which gives 8.575. As a sanity check, since there are 715 people in the sample and 500 in this group, the median should be to the right of halfway through this group, which would be 7.5. And it is.
The time you enjoy wasting is not wasted time.
Bertrand Russell
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