Incidence Prevalanec Stats

Question 1

What

Is incidence

Answer 1

Number of cases in population in a time period

Question 2

What is a prevalence

Answer 2

Number of cases at a specific point in time

Question 3

How to calculate absolute risk

Answer 3

(cases)÷(population) x100

Question 4

How to calculate relative risk

Answer 4

Absolute risk of each population group

Risky group)/ (non risky group

Question 5

How to work out attributable risk

Answer 5

(risk of disease in exposed group) - (risk of disease in non exposed group)
Ur doing the diseased risk - the disease that would happen anyway

Question 6

How to work out number needed to treat

Answer 6

1÷ attributable risk

Always round up

Question 7

Name some wilson and jungner criteria

Answer 7

Important condition 
Known natural history of condition
Condition has latenet/ pre clinical phase
Screening test is senstive, specific, inexpensive and acceptable 
Facilities available to screen 
Worth the money 
Treatment available is effective
Agreed policy on who treat

Question 8

What is sensitivity and how would u calculate it

Answer 8

How many people with the condition are picked up by the test (true positive/everyone who is positive so true positive and false negatives)

Question 9

What is specificity and how to calculate

Answer 9

Does the test identify people who don’t have the disease ie proportion correctly excluded as disease free
(True negatives ÷ everyone who doesn’t have disease)

Question 10

What is positive predictive value and how to calculate

Answer 10

If you get a positive test result, how likely is it u actually have the disease (true positive÷ all positive)

Question 11

What is negative predictive value and how to calculate

Answer 11

If you have a negative test result how likely is it u actually don’t have the disease (true negative ÷ all negative)