Calculating Z = (Pt - Pc) / [ (pq) (1/Nt + 1/Nc) ]1/2 This calculator uses JavaScript. You either do not have a JavaScript capable browser or you have JavaScript turned off. Input variables: Xt = cases in test group = Xc = cases in control group = Nt = total in test group = Nc = total in control group = Interim values: Normality: Pt = risk to test group = Xt / Nt = /= (all values must be > 5) Pc = risk to control group = Xc / Nc = /= Nt*p = p = [Xt + Xc] / [Nt + Nc] = [+] / [+] = Nt*q = q = 1 - p = 1 - = Nc*q = (pq) (1/Nt + 1/Nc) = Nc*p = [ (pq) (1/Nt + 1/Nc) ]1/2 = Z = (Pt - Pc) / [ (pq) (1/Nt + 1/Nc) ]1/2 (copy this value of Z to here to get a p-value)
Input variables:
Xt = cases in test group =
Xc = cases in control group =
Nt = total in test group =
Nc = total in control group =
Interim values:
Normality:
Pt = risk to test group = Xt / Nt = /=
(all values must be > 5)
Pc = risk to control group = Xc / Nc = /=
Nt*p =
p = [Xt + Xc] / [Nt + Nc] = [+] / [+] =
Nt*q =
q = 1 - p = 1 - =
Nc*q =
(pq) (1/Nt + 1/Nc) =
Nc*p =
[ (pq) (1/Nt + 1/Nc) ]1/2 =
Z = (Pt - Pc) / [ (pq) (1/Nt + 1/Nc) ]1/2
(copy this value of Z to here to get a p-value)