At 02:05 PM 10/10/02 +0200, Jan Malte Wiener wrote:
>hi,
>hopefully a simple one ->
>
>let's assume i have data like this:
>subject A: 1,0,1,1,0,1,1,1 -> mean=6/8=0.75
>subject B: 1,1,1           -> mean=3/3=1
>
>weighted arithmetic mean of A+B-> (8*0.75 + 3*1)/11 = 0.82
>-> well that was easy, but what if i do have 20 subjects like this and i
>want to compare their weighted arithmetic mean to the weighted mean of
>another group of 20 subjects ?? i guess i need to weight every single
>subject-mean before running any stat-test. and here is my problem: how
>do i weight the individual subject means ??

if you are comparing, say, using a t test for differences in means as an 
example, the means have been weighted already

if mean 1 is based on n=20 and mean 2 is based on n=15 ... the means have n 
taken into account

the problem arises f someone asks you what is the average of the TWO groups 
... and you just take mean 1 + mean 2 and divide by 2

other than that, i am not quite sure what you are referring to


>thanks for any help,
>jan
>.
>.
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Dennis Roberts, 208 Cedar Bldg., University Park PA 16802
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