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
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 ?
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.
If it ain't broke, fix it until it is.
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？