Measures of Association

Question 1

Sensitivity

Answer 1

The ability of a test to identify correctly those who have the disease
Proportion of diseased people who are correctly identified as “positive” by a test
TP/(TP+FN)
100-%sensitivity=%false negative

Question 2

Specificity

Answer 2

The ability of a test to identify correctly those who do not have the disease
Proportion of non-diseased people who are correctly identified as “negative” by a test
TN/(TN+FP)
100-%specificity = % false positive

Question 3

Morbidity

Answer 3

Rate of disease in a population
Can be described by cumulative incidence proportion, incidence rate, prevalence, attack rate

Question 4

Cumulative incidence proportion

Answer 4

Period of time during which all of the individuals in a proportion are considered to be at risk for the outcome
Measure of risk

Question 5

Incidence rate

Answer 5

Number of new cases of a disease that occur during a specified period of time in a population at risk for developing the disease
Measure of morbidity

Question 6

Incidence rate per 1000

Answer 6

New cases/those at risk x 1000

Question 7

Prevalence

Answer 7

Number of affected persons present in the population at a specific time divided by the number of persons in the population at the time
Measure of morbidity

Question 8

Attack rate

Answer 8

The number of people exposed to something and get the associated outcome divided by the total number of people exposed
Measure of morbidity

Question 9

Mortality rate

Answer 9

Number of deaths from a cause in a certain population over a specific period of time

Question 10

Standardization

Answer 10

Set of techniques used to remove the effects of differences when comparing two or more populations

Question 11

Direct standardization

Answer 11

Rate of death/disease that would have been observed in the study population if it had the same age distribution as in the standard population

Question 12

Indirect standardization

Answer 12

Compares the rate of death/disease observed in the population to the expected rate from the standard population

Question 13

Risk Ratio

Answer 13

Ratio of the risk of disease in exposed individuals to the risk of the disease in unexposed individuals
a/(a+b) / c/(c+d)

Question 14

Odds Ratio

Answer 14

The ratio of the probability of occurrence of an event to that of non-occurrence
(a x d) / (b x c)

Question 15

When are risk ratios used

Answer 15

Prospective, cohort studies

Question 16

When are odds ratios used

Answer 16

Retrospective, case control studies

Question 17

Attributable risk

Answer 17

The amount or proportion of disease incidence or risk that can be attributed to a specific exposure
AR = Risk exposed - risk unexposed

Question 18

Population attributable risk

Answer 18

The attributable risk of an entire population whether or not all in the population have direct exposure

Question 19

Hazard Ratio

Answer 19

The rate at which an unfavorable event occurs; commonly used in survival analysis

Question 20

Confidence interval

Answer 20

Numerical range used to describe how reliably study results reflect the entire population

Question 21

Number needed to treat

Answer 21

Number of patients who would have to receive the treatment for one of them to benefit

Question 22

Number needed to harm

Answer 22

Number of patients who receive a treatment before one adverse event occurs

Question 23

Confidence interval interpretation

Answer 23

General interpretation statement: It is likely that the true mean difference between the two groups is somewhere between the first number in the range and the second number in the range