Measures of Frequency, Association and Impact Flashcards Preview

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Flashcards in Measures of Frequency, Association and Impact Deck (28)
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1

What are the basic measures?

Count- no comparison
Proportion
Odds- 4:1
Rate- needs time

2

What are the two most important measures of frequency?

Incidence
Prevalence

3

What is the difference between incidence and prevalence?

Incidence is frequency of new cases during a period where as prevalence is the proportion of all animals in a specific time

4

What is the commonly used measures of incidence?

Cumulative incidence/ incidence risk

5

What does incidence show about a disease?

The amount of risk of contracting the disease

6

What is needed for incidence?

A clear case definition, surveillance programme which identifies cases, to show its a new case

7

What is cumulative incidence?

The proportion of disease-free individuals developing a given disease over a specified time

8

How is cumulative incidence calculated?

Number of new cases during period/
population at risk during same period

9

How is prevalence calculated?

Number of cases at time/
total number of animals at risk at time

10

What is the difference between point and period prevalence?

Point is a single point in time, period is number of cases over defined period of time

11

What does prevalence show about a disease?

How widespread a disease is

12

What is needed for prevalence?

Cross sectional studies, no idea about temporality

13

How does duration of a disease effect incidence and prevalence?

High incidence but short duration causes low prevalence
Low incidence but long duration causes high prevalence

14

What are measures of association used to assess?

The magnitude of the relationship between risk factor and outcome

15

What are the 2 types of relative measures?

Relative risk, odds ratio

16

What are the 2 types of absolute measures?

Risk difference, attributable fraction,

17

What kind os studies are used for relative risk?

Cohort and cross sectional

18

How is the relative risk ratio calculated?

risk of disease in exposed/
risk of disease in unexposed

19

What does relative risk measure?

The strength of association

20

What is odds?

The probability of an event occurring divided by the probability of the event not occurring

21

How is odds ratio calculated?

Odds of disease in exposed/
Odds of disease in non-exposed

22

How can odds be interchanged?

Odds of exposure can be used

23

What king of studies is odds ratio used?

Case-control studies

24

What does it mean if the RR/OR are below 1, equal to 1, over 1?

<1- decreased risk
=1- no change
>1- increased risk

25

What can make a RR/OR insignificant?

If the confidence interval crosses 1

26

What is the problem of measures of association?

Don't show the frequency of disease or the amount of disease that results

27

What is the measure of impact of exposed?

Attributable risk

28

How is attributable risk calculated?

Risk among the exposed- risk among the unexposed