A screening test for COPD in women is being evaluated. Of the 100 women later confirmed to have COPD, 42 had a positive screen. Of the 150 women later determined to not have COPD, only 8 had a positive screen. Suppose in our population of interest, 20% of women have COPD. That is, P(COPD) = 0.20 in our population.

a) Fill in the frequency table from the information above.

COPD No COPD Positive Negative

b) Using the frequency table above, calculate the sensitivity and specificity of the screening test for COPD.

Se =

Sp =

c) Calculate the PPV of the test = P(COPD | Positive) for our population of interest. Remember that you can't calculate this directly from the conditional probability and must calculate it using Bayes rule.

d) What is the probability that a woman who does not have COPD will have a positive screen?