Chapter 9: Measures of Effect

Question 1

Attributable risk

Answer 1

A measure of risk difference. In a cohort study, refers to the difference between the incidence rate of a disease in the exposed group and the incidence rate in the nonexposed group.

Question 2

Confidence interval

Answer 2

A computed interval of values that, with a given probability, is said to contain the true value of the population parameter; a measure of uncertainty about a parameter estimate. An example is the confidence interval about a relative risk measure.

Question 3

Effect measure

Answer 3

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

Question 4

Etiologic fraction

Answer 4

Proportion of the rate of disease in an exposed group that is due to the exposure.

Question 5

Mortality difference

Answer 5

Measure of the difference between an exposed and nonexposed population in the frequency of death (see Risk difference).

Question 6

Multiple causality (multicausality or multifactorial etiology)

Answer 6

A portrayal of causality wherein several individual, community, and environmental factors may interact to cause a particular disease or condition.

Question 7

Null hypothesis

Answer 7

A hypothesis of no difference in a population parameter among the groups being compared.

Question 8

P value

Answer 8

An assessment that indicates the probability that the observed findings of a study could have occurred by chance alone.

Question 9

Population etiologic fraction (attributable fraction in the population)

Answer 9

Proportion of the rate of disease in the population that is due to an exposure. It is calculated as the population risk difference (Ip – Ine) divided by the rate of disease in the population (Ip).

Question 10

Population risk difference

Answer 10

Difference between the incidence rate (risk) of disease in the nonexposed segment of the population (Ine) and the overall incidence rate (IP): (IP – Ine). It measures the benefit to the population derived by modifying a risk factor.

Question 11

Prevalence difference

Answer 11

Measure that computes the difference in prevalence between an exposed and nonexposed population (see Risk difference).

Question 12

Rate difference

Answer 12

Measure of the difference between two rates (for example, incidence rates) between exposed and nonexposed populations (see Risk difference).

Question 13

Risk difference (also, attributable risk)

Answer 13

Difference between the incidence rate of disease in the exposed group (Ie) and the incidence rate of disease in the nonexposed group (Ine): risk difference = Ie – Ine.

Question 14

Significance level

Answer 14

Chance of rejecting the null hypothesis when, in fact, it is true.