Screening

Question 1

Sensitivity

Answer 1

Proportion of cases which the test correctly detects

Question 2

Specifity

Answer 2

Proportion of non-cases which the test currently detects

Question 3

PPV

Answer 3

The proportion of positive tests who are cases

Question 4

NPV

Answer 4

The proportion of negative tests who are not cases

Question 5

Lead-time bias

Answer 5

Early diagnosis falsely appears to prolong survival

Question 6

Length time bias

Answer 6

Screening programmes better at picking up slowing growing, unthreatening cases than aggressive, fast growing ones.