Lecture 3: Measures Of Association Flashcards Preview

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Flashcards in Lecture 3: Measures Of Association Deck (37)
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1

Creating possible alternatives to events that already happened, for example someone got a disease instead of not having had it.

Counterfactual thinking/theory

Counter-to the-facts

2

What assumption does counterfactual theory require?

Assumption of exchangeability

3

What is always in the columns of a 2x2 chart?

Disease/Outcome

4

Absolute differences is found by doing what with frequencies?

Subtracting

5

Relative differences is found by doing what with frequencies?

Dividing

6

True or False:

Absolute differences are always larger than relative differences

False

Absolute is smaller

7

Define ‘risk’

The probability of an outcome in an individual group, exposed or not exposed

8

Is risk considered a proportion or ratio?

Proportion

It is a simple percentage

9

Absolute risk reduction formula

Subtracting the absolute risk of those exposed - AR not exposed

10

Relative risk reduction formula

ARR
——
Absolute Risk of the unexposed

11

What does NNT stand for

Number needed to treat

12

What does NNH stand for?

Number needed to harm

13

Doe we want NNH or NNT to be smaller?

We want NNT to be small

We want NNH to be huge

14

Give an example of NNT

It would take 8 patients on a drug for 1 person to get positive benefits

1 in 8 patients on this drug will get positive benefits

15

How to calculate NNT/NNH?

1 divided by Absolute risk reduction

1
——
ARR

16

how to calculate risk ratio?

risk of outcome in exposed//////risk of outcome non-exposed=placebo

17

The exposure or treatment group of interest, is always in the denominator when calculating risk ratio. T/F

false
always in numerator

18

if risk ratio is >1

the outcome is more likely to occur in the study than in the unexposed group

19

if risk ratio is <1

the outcome is less likely to occur in the study group than the unexposed group

20

if risk ratio = 1

outcomes are equally likely in both groups

21

other names for risk ratio

odds ratio
hazard ratio

22

interpret a RR = 1.53

53% more likely

23

interpret a OR = 2.35

outcome is 2.35 times more likely

24

interpret a HR = 0.75

outcome is 25% less likely to occur

25

when interpreting a RR/OR/HR, there are 3 things you must include in your interpretation.....

1. groups you are comparing
2. direction of your results
3. magnitude

26

visual representation of ratio data, horizontal plot allowing the comparison of multiple ratios and their differences from 1.0

forest plot

27

OR INTERPRETATION: association between baseline characteristics of firearm and pedestrian motor vehicle injury hospitalizations. Reference: white, Hispanic OR = 1.43

hospitalization due to firearm injury or pedestrian motor vehicle injury, is 43% more likely to occur in Hispanic ethnicities than white.

28

Odds is a ……?

ratio

29

define 'odds'

frequency of an outcome occurring vs. not occurring
or
frequency of exposure vs. frequency of not being exposed
or
occurring/not occurring within one group

30

relate odds calculation to a 2x2 table

A/C or B/D