Screening Validity

Question 1

Two errors in screening

Answer 1

False positive - refer well people for unnecessary investigation
False negative - fail to refer people who actually have disease

Question 2

Features of test validity

Answer 2

Sensitivity, specificity, positive predictive value, negative predictive value

Question 3

Sensitivity in test validity

Answer 3

Proportion of people with the disease who test positive

Use disease present column to work out

Question 4

Specificity in test validity

Answer 4

Proportion of people who do not have the disease that test negative
Use disease absent column

Question 5

Features of sensitivity and specificity

Answer 5

Function of the characteristics of the test

When same test is applied to different populations it will have the same sensitivity and specificity

Question 6

Positive predictive value

Answer 6

The probability that if you test positive, you actually have the disease
Use positive test row

Question 7

What effects positive predictive value

Answer 7

Prevalence - if high prevalence, positive predictive value is likely to be higher (good at recognising)

Question 8

Negative predictive value

Answer 8

Proportion of people who test negative who actually do not have the disease
Use negative test row