Statistics

Question 1

Sensitivity

Answer 1

True positives/ (True positive+ False negatives)

Correctly identifies patient with disease

Question 2

Specificity

Answer 2

True negatives/ (True negatives + False positives)

Question 3

PPV

Answer 3

True Positives/ (True Positives+ False Positives)

Probability of patient who has positive results actually having the disease

Question 4

NPV

Answer 4

True negatives/ (true negatives+ false negatives)

Negative test results truly do not have the diseease

Question 5

How does prevalence effect NPV and PPV

Answer 5

Prevalence affects PPV and NPV differently. PPV is increasing, while NPV decreases with the increase of the prevalence.

Question 6

How to calculate accuracy

Answer 6

of test correct/ all

Question 7

How to calculate the likelihood ratio

Answer 7

LR= sensitivity/(1-Specificity)

How much more likely is it that a patient with a positive test has disease compared with a patient with a negative test

Question 8

What is the difference between incidence and prevalence

Answer 8

Incidence refers to the occurrence of new cases in a specific health-related state during a time period, whereas prevalence measures the proportion of subjects who are in the state at a point in time

Question 9

On a accuracy chart what is the x and what is the y

Answer 9

X= disease status
Y= Test status