Papanicolau (Pap) smear screening is currently the accepted method for early detection of cervical cancer and women with an abnormal Pap smear result are referred to a gynaecologist for colposcopy for...

Papanicolau (Pap) smear screening is currently the accepted method for early detection of cervical cancer and women with an abnormal Pap smear result are referred to a gynaecologist for colposcopy for definitive diagnosis. To see whether repeat Pap screening would reduce the number of unnecessary referrals, 110 women with an abnormal Pap smear were given both a second Pap smear and colposcopy. The colposcopy showed that 13 women had high-grade lesions and 97 did not. The result of the repeat Pap test was abnormal for 12 of the women with and 72 without high-grade lesions

(a) Construct a 2 2 table comparing repeat Pap test with colposcopy. (b) Calculate the sensitivity and specificity of the repeat Pap test. (c) What is the positive predictive value of the repeat Pap test? (d) What is the probability that a woman whose repeat Pap test gives a negative result actually has a high-grade lesion? (e) Could a second Pap smear be used to identify women who should be referred for colposcopy?