More math

Question 1

CI with loss to follow up eqt

Answer 1

CI= (# new cases)/[(pop at risk)-(w/2)].. over time t

Question 2

what is the difference between confirmed and probable cases

Answer 2

Probable case usually lacks laboratory confirmation or epidemiological link

Question 3

When initiating an investigation, you typically want a case definition that has higher _ to improve efficiency

Answer 3

When initiating an investigation, you typically want a case definition that has higher sensitivity to improve efficiency

Question 4

Give two reasons why a case control study is a desirable design in this case

Answer 4

• Disease is rare*
• Population-at-risk is unclear/incompletely known.*

Question 5

When you have a lot of withdrawals which measure of frequency do you use?

Answer 5

IR

Question 6

Give two reasons why you choose retrospective cohort study

Answer 6

Short latent period, well-defined population at risk

Question 7

Sensitivity

Answer 7

Pr(T+,D+)=TP/(TP+FN)

Question 8

Specificity

Answer 8

Pr(T-,D-)=TN/(TN+FP)

Question 9

PPV

Answer 9

Pr(D+,T+)=TP/(TP+FP)

Question 10

NPV

Answer 10

P(D-,T-)=TN/(TN+FN)