Use Table Characterisctic B Characteristic A Present Absent

Use Table

                                 Characterisctic B

Characteristic A         Present       Absent      Total

Present                    p11              p12           p1.

Absent                     p21              p22          p2.

Total                        p.1               p.2           1

Prove that:

p12-p.1p.2= -(p11-p1.p.1),     p21-p2.p.1= - (p11-p1.p.1), p22-p2.p.2= p11-p1.p.1

[hint: because p11 +p12=p1, therefore p12=p1.-p11. Use the fact that 1-p.2=p.1.]

Solution