# Chapter 9: Measures of Effect Flashcards

1
Q

What is an effect measure?

A

a quantity that measures the effect of a factor on the frequency or risk of a health outcome

• Attributable fractions: measure the fraction of cases due to a factor
• Absolute effects: risk and rate differences measure the amount of a factor adds to the risk or rate of a disease
• Relative effects: risk and rate ratios measure the amount by which a factor multiplies the risk or rate of disease
2
Q

What is the difference measure of association?

A

a type of comparison. Used to compare the disease burden in 2 groups. A way to do that is to calculate the absolute difference in disease frequency

3
Q

What is another name for difference measure of association?

A

Attributable risk

4
Q

Risk difference?

A

the difference between the incidence rate of disease in an exposed group and a non exposed group
-RD= I(e)-I(ne)

5
Q

Population risk difference?

A

a measure of the benefit to the population derived by modifying a risk factor
-I(p)total incidence rate= I(e)P(e)+ I(ne)P(ne)*

6
Q

What is an etiologic fraction? Equation?*

A

defined as the proportion of the rate in the exposed group that is due to the exposure
-(I(e)-I(ne)/I(e)) page 950

7
Q

Another name for etiologic fraction?

A

Attributable proportion/fraction

8
Q

Population fractions?***

A

page 955-957

9
Q

What is a null hypothesis?

A

there is no difference in pop. parameters among the groups being compared

10
Q

P value?

A

indicates the probability that the findings observed could have occurred by chance alone

11
Q

What is a confidence interval?

A

a CI is a statisitical measure. Computed interval of values that w/ a given probability, contains the true value of the population parameter/estimate
-Can be calculated for odds ration as well as other relative risks, etc.

12
Q

What is a deterministic model?

A

it claims that a cause is invariably followed by an effect

• Ex: laws related to gravitation, motion, electrostatics
• from the philosophy of determinism
13
Q

What is a necessary cause?

A

a factor whose presence is “required” for the occurrence of the effect

14
Q

What is a sufficient cause?

A

a cause that is sufficient by itself to produce the effect

15
Q

Deterministic causality?

A
• necessary and sufficient
• necessary but not sufficient
• sufficient but not necessary
• neither necessary nor sufficient
• pages 978-979
16
Q

What is a stochastic process?

A

one that incorporates some element of randomness. A cause is associated with the increased probability that an effect will happen
-Ex: radiation exposure & carcinogenesis. Exposure to radiation from radioactive nuclear materials is related to the probability that the exposed person will develop radiation-induced cancer

17
Q

What is multiple causation?

A

Also called multifactorial etiology. the requirement that more than one factor is present for a disease to develop.

18
Q

What is the web of causation?

A

implicates broad classes of events and represents an incomplete portrayal of reality. a web like structure that intertwines different causes for a disease or something
-Figure 9-14 (page 982)

19
Q

What is a wheel model?

A

explains the etiology of disease by calling into play host and environment interactions. similar to the epidemiologic triangle and web of causation w/ respect to multiple causality. another form
-Figure 9-15 (page 984)

20
Q

What is the causal pie model?

A

indicates that a disease may be caused by more than one causal mechanism (a sufficient cause). another model of multiple causality
-Figure 9-16 (page 986)

21
Q

What are significance tests?

A

a statistical procedure that when applied to a set of observations results in a p-value relative to some hypothesis

22
Q

What is clinical significance?

A

describes the ability of a factor to impact health

• What is the benefit or harm yo people?
• Does the finding have practical application?
• Is there a clinically relevant benefit or harm?
• Are we sure the benefit
23
Q

Large sample size produce?

A

Narrow CIs

24
Q

Small sample size produce?

A

Wide CIs

25
Q

Difference between absolute and relative effect?

A

Absolute effect looks at excess risk. Relative effect looks at the strength of association

26
Q

If the exposure is positive?

A

It causes risk*

27
Q

If the exposure is negative?

A

It is more protective*

28
Q

What are the 3 measures of effect?

A
• Absolute effects
• Relative effects
• Attributable (etiologic) fractions
29
Q

What is a risk factor?

A

an exposure that’s associated w/ a disease, morbidity, mortality, or adverse health outcome

30
Q

Is a risk factor independent or dependent?

A

Independent; b/c it’s what causes the disease

31
Q

Is a risk factor the same as risk? Why or why not?

A

No. A risk factor is not risk. Risk is the probability of developing the outcome (incidence)

32
Q

Is outcome independent or dependent?

A

Dependent; b/c it’s the result of the exposure or risk factor

33
Q

An absolute effect may be based on differences in what?

A
• Prevalence
• Cumulative incidence
• Incidence density
• Mortality
34
Q

Relative risk?

A

RR; Ratio of risk for those exposed relative to not exposed

-(a/a+b) / (c/c+d)

35
Q

Odds Ratio?

A

OR; Ratio of odds for those exposed relative to those not exposed

36
Q

Attributable risk?

A

Absolute excess risk among those exposed that is attributable to the exposure
-(a/a+b) - (c/c+d)

37
Q

Attributable fraction?

A

Fraction of disease among those exposed that is attributed to the exposure
-(a/a+b) - (c/c+d) / (a/a+b)

38
Q

What is association?

A

an identifiable relationship between exposure and disease

39
Q

What is cause?

A

an agent or exposure that brings about an event or such as disease or other health outcome