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#1 Help Me ! » another odds ratio case » 2013-12-09 23:21:34

Replies: 1

in online game, two team fight against each other

team a   strength  73% ,which corespond to 100% (for conveniece, here note 73)
team b   strenth   46

then odds ratio =73/(100-73)/ (46/(100-46)=73/27/(45/55)
no problem here

suppose team;s strength divided into two part  attck and defense
team a  attack=44    defense=6
team b  attack=64    defense=33
where 100 correspoinds to the best rank

in odds ratio formula, winthin a group ,  p,  100-p

since attack+defense is not equal to 100, which puzzled me.
I use several method,

for conveniece
team a attack note m
team a defense n
team b attck o
team b defense p

method 1
strenth=(attack +defense)/2   algebra average value
then use the fumula of odds ratio
odds ratio=((m+n)/2)(100-(m+n)/2)/ ( ((o+p)/2)/(100-((o+p)/2)))

method 2
strength=sqrt((attack +defense) geometry average value

methd 3
regard defense is unlike probilities,juse use odds ratio formula directly
odds ratio=m/p /(o/n)

method 4 

odds ratio= m/(100-m)/(p/(100-p))/  (o/(100-o)/(n/(100-n)))

method XX

which is right? or they were all wrong ? any solution pls give me help?

how to calculate odds ratio?

#2 Re: Help Me ! » odds ratio problem » 2013-12-09 15:39:08

Tks for your reply.  I input a wrong number that Number in 1st group:    a=26
  not 25    if 25  ,2 .777  is  right.
like formula Odds ratio = (a/c) / (b/d) ,what is the formula for probability?

#3 Help Me ! » odds ratio problem » 2013-12-09 04:31:33

Replies: 3

I input a,b,c,d  use odds ratio calculator

Cases with positive outcome
Number in 1st group:    a=25
Number in 2nd group:    b=15
Cases with negative outcome
Number in 1st group:    c=18
Number in 2nd outcome:    d=30

and calculate

Odds ratio    2.8889
95 % CI    1.2184 to 6.8497
z statistic    2.408
P = 0.0160

I know odds ratio is Odds ratio = (a/c) / (b/d)
my question is
what z statistic    and p mean ?

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