Risk, Summary measures to Binary data

Question 1

What is the formula for RISK

Answer 1

Number of events observed
divide by
Number in group

eg 150 people in a group 15 get a rash- what is the risk
15/150- 0.10 or 10%

Question 2

what do rates always have attached

Answer 2

time period- 60 per 100,000

Question 3

what is the equation for difference in proportions

Answer 3

d-proportions = p-exposed – p-unexposed

also know as risk difference

Question 4

what is Absolute Risk Difference(ARD)

Answer 4

absoule additinal risk of an event due to exposure

Question 5

equation for ARD

Answer 5

ARD =| pexposed – punexposed|

Question 6

The proportion of subjects who develop the disease in the exposed group is

Answer 6

a/(a+c)- rember in a 2x2 table

a b
c d

Question 7

The proportion of subjects who develop the disease in the unexposed group is

Answer 7

b/(b+d)

Question 8

how to find diffrence by proportions

Answer 8

dproportions = pexposed – punexposed- known as risk diffrence

Question 9

risk for devloping a disease for exposed group in 2x2 table

Answer 9

a/(a+c)

Question 10

risk for devloping diease in unexposed in 2x2 table

Answer 10

b/(b+d)

Question 11

relative risk of devloping disease for the exposed compred to the unexposed

Answer 11

pexposed-punexposed

risk of devloping in exposed-risk of devloping in unexposed

Question 12

if the risk for the exposed in 0.80
and for the unexposed it is 0.18
what is the relative risk

Answer 12

0.80/0.18= 4.5

Question 13

what is the number needed to treat equation

Answer 13

1/ARD
example is the ard is 0.62
than 1/0.62- 1.6- round up to 2- 2 extra people would be needed in the group for 1 extra outcome to be seen

Question 14

what is number need to harn

Answer 14

1/ARD- ignore any negative numbers

Question 15

how do you work out an odds

Answer 15

Propotion/ (1-P)

Question 16

odds RATIO equation

Answer 16

punexposed/(1-punexposed)