EPID 5201 HW 6 Question 4

4. 2x2 tables are below a.) Sensitivity = P(T+|D+) = 35/50 = 70%

Specificity = P(T-|D-) = 60/100 = 60%

b.) With prevalance of 5% and assuming a population of 10,000 people

P(D+|T+) = 350/4150 = .0843 -> 8.43% of those who tested positive for CTS actually have CTS

P(D-|T-) = 5700/5850 = .9744 -> 97.44% of those who tested negative for CTS do not have CTS.

c.)

RR = P(D+|T+)/P(D+|T-) = 0.0843/.026 = 3.24

Someone who tested positive for CTS is more likely to have CTS than someone who tested negative.

##       CTS No CTS Total
## +      35     40    75
## -      15     60    75
## Total  50    100   150

##         CTS No CTS Total
## +       350   3800  4150
## -       150   5700  5850
## Total   500   9500 10000