Behavioral Science and Social Sciences

Question 1

the usual, expected rate of disease over time; the disease is maintained without much variation within a region

Endemic/Pandemic/Epidemic

Answer 1

Endemic

Question 2

occurrence of disease in excess of the expected rate; usually presents in a larger geographic span than endemics (epidemiology is the study of epidemics)

Endemic/Pandemic/Epidemic

Answer 2

Epidemic

Question 3

worldwide epidemic

Answer 3

Pandemic

Question 4

visual description (commonly histogram) of an epi demic curve is disease cases plotted against time; classic signature of an epidemic is a “spike” in time

Answer 4

Epidemic curve

Question 5

is the rate at which new events occur in a population

Answer 5

Incidence rate (IR)

Question 6

is the cumulative incidence of infection in a group of people observed over a period of time during an epidemic, usually in relation to food-borne illness. It is measured from the beginning of an outbreak to the end of the outbreak.

Answer 6

Attack rate

Question 7

is all persons who experience an event in a population. The numerator is all individuals who have an attribute or disease at a particular point in time (or period of time). The denominator is the population at risk of having the attribute or disease at that point in time or midway through the period.

Answer 7

Prevalence

Question 8

True or false: Prevalence is a measurement of all individuals (new and old) affected by the disease at a particular time, whereas incidence is a measurement of the number of new individuals who contract a disease during a particular period of time.

Answer 8

True

Question 9

is the actual measured rate for a whole population, e.g., rate of myocardial infarction for a whole population. Use caution using the crude rate, though. Imagine that in a given city, there are a lot of older, retired people—the crude rate of myocardial infarction will appear higher even though the rate for each age group has not actually changed.

Answer 9

Crude rate

Question 10

is the actual measured rate for subgroup of population, e.g., “age-specific” or “sex-specific” rate. For instance, the rate of myocardial infarction among people age >65 in the population or the rate of breast cancer among the female population. If you are provided specific rates, you can calculate the crude rate. The crude rate of an entire population is a weighted sum of each of the specific rates. The weighted specific rates that are added together is calculated in the table below.

Answer 10

Specific rate

Question 11

is adjusted to make groups equal on some factor, e.g., age; an “as if” statistic for comparing groups. The standardized rate adjusts or removes any difference between two populations based on the standardized variable. This allows an “uncontaminated” or unconfounded comparison.

Answer 11

Standardized rate (or adjusted rate)

Question 12

is the probability of correctly identifying a case of disease. In other words, it is the proportion of truly diseased persons in the screened population who are identified as diseased by the screening test. This is also known as the “true positive rate.”

Answer 12

Sensitivity

Question 13

is the probability of correctly identifying disease-free persons. Specificity is the proportion of truly nondiseased persons who are identified as nondiseased by the screening test. This is also known as the “true negative rate.”

Answer 13

Specificity

Question 14

is the probability of disease in a person who re ceives a positive test result. The probability that a person with a positive test is a true positive (i.e., has the disease) is referred to as the “predictive value of a positive test.”

Answer 14

Positive predictive value (PPV)

Question 15

is the probability of no disease in a person who receives a negative test result. The probability that a person with a negative test is a true negative (i.e., does not have the disease) is referred to as the “predictive value of a negative test.”

Answer 15

Negative predictive value (NPV)