CAL 2

Question 1

How do you calculate an odds ratio

Answer 1

number of case x number of control exposed / number of controls exposed x number of case

Question 2

What odds ratio is associated with no effect

Answer 2

1:1 or 0
if a confidence interval for an odds ratio contained 1, then the associated P value is greater than 0.05
if a confidence interval for an odds ratio does not contain one then the associated P value is less than 0.05

Question 3

what is a chi squared test

Answer 3

• this is when the P value is calculated by comparing the observed numbers in the table to those expected if there was no association between the two groups and stimulus

Question 4

How do you work out the risk of dying

Answer 4

number of deaths/ number of patients in group

Question 5

how do you work out the risk of dying per 100

Answer 5

risk of dying x 100

Question 6

How do you work out the relative risk of dying

Answer 6

risk of dying per 100 in experiment group/ risk of dying per 100 in placebo group

Question 7

How do you work out percentage increase

Answer 7

original - new/new

Question 8

how do you work out percentage decrease

Answer 8

original - new/ original

Question 9

what does the P value have to be in order to be significant

Answer 9

P value has to be less than 0.05 to be significant

Question 10

if there is a 1 present

Answer 10

it is not significantly significant