RISK

Question 1

define risk

Answer 1

probability that an event will occur in a group, whether it be a good or a bad event.

Question 2

what is p value

Answer 2

probability and refers to the likelihood that the observed difference (or something more extreme) was observed by chance.

Question 3

define odds

Answer 3

the average frequency of a loss to the average frequency of a win.

Question 4

Relative Risk is used for

Answer 4

to compare the risk in two different groups of people (e.g. smokers and non-smoker)

Question 5

Odds Ratio is used for

Answer 5

a measure of association between an exposure and an outcome (e.g. smoking and cancer)

Question 6

when is RR used

Answer 6

usually used in prospective cohort studies.

Question 7

when is OR used

Answer 7

case-control studies and sometime in cohort studies (where the incidence is less than 10%).

Question 8

Absolute Risk is used for

Answer 8

an individual risk of developing a disease over a time period (e.g. smokers and cancer)

number of events (such as a disease) that occurred in a group, divided by the number of people in that group.

Question 9

what is Relative Risk Reduction

Answer 9

decrease in probability of an event occurring due to a lifestyle change or treatment.

Question 10

look at contingency tables

Answer 10

look at contingency tables

Question 11

what is the relative risk formula

Answer 11

A/(A+B) / C(/C+D)

Question 12

RR = 1 means…

Answer 12

exposure is not associated with the outcome

Question 13

RR < 1 means…

Answer 13

risk of the outcome is decreased by the exposure;

Question 14

RR > 1 means…

Answer 14

risk of the outcome is increased by the exposure.

Question 15

odds ratio equation

Answer 15

(AD) / (BC)

Question 16

OR = 1 means

Answer 16

exposure is not associated with the outcome

Question 17

OR < 1 means

Answer 17

there are lower odds of the outcome happening with the exposure

Question 18

OR > 1 means

Answer 18

there are higher odds of the outcome happening with the exposure

Question 19

what is a 95% confidence interval (CI)

Answer 19

a range of values that you can be 95% certain contains the true mean of the population

Question 20

CI analysis

Answer 20

RR or the OR = 1, or the CI = 1, then there is no significant difference between treatment and control groups.

RR/OR >1, and the CI does not include 1, events are significantly more likely in the treatment than the control group.

RR/OR <1, and the CI does not include 1, events are significantly less likely in the treatment than the control group.

Question 21

When do we use odds and probabilities?

Answer 21

When the outcome is rare (i.e., < 10%) the odds and the probability will be similar. Therefore the OR will provide a reasonable estimation of the RR.

Question 22

when could the OR be an overestimate of the RR

Answer 22

When the outcome is common in the population (i.e., >10%), the odds will be higher than the probability

treatment seems better than it is

Question 23

what is AR and AR reduction

Answer 23

AR = size of your own risk

AR reduction = the number of percentage points your own risk goes down if you do something protective

Question 24

what is the ARR equation

Answer 24

ARR = AR unexposed – AR exposed

negative number

Question 25

what is another equation for RR based on AR

Answer 25

RR= AR exposed / AR unexposed

Question 26

what is another equation for RRR based on AR

Answer 26

RRR = (AR unexposed – AR exposed) / AR unexposed

Question 27

RR and AR should be presented together

Answer 27

RR and AR

Question 28

how to calculate odds of exposure in case/non case

Answer 28

either a/c

or b/d