Risk factor calculator:

1. Input:

	cases	Total
Test	Xt=	Nt=
Control	Xc=	Nc=

2. Calculate upper and lower limits of Xt:

Enter a value for Nt (the number of test cases) in the middle box; then click the Compute button:

Xt''	Xt	Xt'

3. Check interim values

Pt	=		Pt'	=
Pc	=		Pt''	=
p	=		q	=

4. calculate upper' and lower'' limits of Pe:

Pe' = (Pt' - Pc) / (1 - Pc)	=
Pe'' = (Pt'' - Pc) / (1 - Pc)	=

5. calculate R:

R = Pe' / D

=