Theme 1, 2 and 3 formulae

Question 1

how do you work out risk?

Answer 1

risk = number of exposed people with the disease / total number of exposed sample

Question 2

relative risk?

Answer 2

relative risk = risk in exposed group / risk in non-exposed group

Question 3

attributable risk?

Answer 3

attributable risk = risk in exposed group - risk in non exposed group

Question 4

attributable risk percent?

Answer 4

attributable risk percent = attributable risk / incidence of disease in exposed group

Question 5

number needed to harm (NNH)?

Answer 5

NNH = 1 / attributable risk

Question 6

number needed to treat (NNT)?

Answer 6

1/ attributable risk reduction

Question 7

Odds?

Answer 7

odds = number of exposed people with the disease / number of exposed people without the disease

Question 8

odds ratio?

Answer 8

odds ratio = odds in exposed group / odds in non - exposed group