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## Topic review (newest first)

bobbym
2013-12-10 20:49:58

Hi;

You can get a probability from the odds.

extjsjquery
2013-12-10 14:39:08

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？

bobbym
2013-12-10 03:42:17

Hi;

Are you doing something like this?

I am getting an OR = 2.7777777777

Also I think you mean P rather than p.

Z scores are measures of standard deviation. P is a probability.

extjsjquery
2013-12-10 03:31:33

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

Results
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 ?