Epidemiology and Measurement Error Note Review

Detailed vocabulary flashcards covering basic epidemiology principles, measurement error, misclassification, disease transmission, and epidemic patterns.

Subjective data

Data subject to recall bias, non-understanding, and sensitive questions.

Validity

The extent to which a test measures or predicts what it is supposed to (e.g., self-reported body weight vs. scale).

"Gold Standard"

The reference used to compare against when assessing validity.

Test sensitivity

The proportion of people WITH the disease who test positive, calculated as $\text{True Positives} / \text{population}$.

Test Specificity

The proportion of people WITHOUT disease who test negative, calculated as $\text{True negatives} / \text{population}$.

differential misclassification

Misclassification based on the presence or absence of disease (outcome); it is non-random, group-based, and can exaggerate or minimize associations.

Non-differential misclassification

Misclassification that can occur in either group; it is random and leads to an attenuation of Odds Ratio association.

Exposure Dose

The quantity or level of exposure.

Exposure time

The point in time when the exposure occurred.

Cumulative dose

The product of $\text{duration} \times \text{frequency} \times \text{intensity}$.

Etiological time window

The specific time period where the exposure is most likely to cause disease.

reverse causality

When researchers mistake a symptom of disease for the cause of disease (e.g., fiber supplements taken as a result of constipation from colon cancer being blamed for the cancer).

Induction period

The interval between the action of a cause (when the etiological period finishes) and the onset of the disease.

Latent period

The time interval from the onset of disease to the time of diagnosis.

Incubation period

The interval between the initial infection and the appearance of the first signs and symptoms.

Fomite

An inanimate object that can harbor and transmit pathogens.

Vehicle

A medium (e.g., water) that carries an agent from a reservoir to the human host.

Vector

An invertebrate animal that transfers infection from one host to another.

Reservoir

The habitat where an infectious agent lives (humans, animals, water).

Zoonosis

A disease that can pass from animals to humans.

Primary Prevention

Interventions that occur prior to exposure to prevent the occurrence of disease.

Secondary Prevention

Interventions that occur after exposure to prevent the progression of the disease.

Tertiary Prevention

Long-term interventions and care to reduce limitations and disability from disease.

Prevalence

Calculated as $\text{Incidence} \times \text{Disease Duration}$.

Incidence rate $I(t)$

The product of $\text{Prevalence of Infected Persons P(t)} \times \text{Contact process C} \times \text{Transmission Probability (B)}$.

Transmission Probability

The probability of infection being transmitted during contact, calculated as \text{Total } \text{# infections} / \text{Total } \text{# contacts}.

secondary attack rate

Calculated as \text{# of new cases among contacts} / \text{total # of contacts}.

Basic Reproductive Number ($R_0$)

The average number of secondary cases that develop from a single initial case.

Epidemic

An occurrence of disease above the normal expectancy.

Outbreak

An epidemic that is confined to a local area.

Common source point

An epidemic curve from one source where the rise and fall in the number of cases are both rapid.

Common Source Intermittent

An epidemic curve characterized by sporadic rises in the number of cases.

Common Source Continuous

A large number of cases from continuous exposure; the curve rises slowly, plateaus, and then slows gradually.

propagated non-progressive

An epidemic curve resulting from a single exposure with no secondary cases.

propagated progressive

An epidemic curve resulting from person-to-person transmission, characterized by new waves of cases and multiple peaks.

Mixed epidemic curve

Occurs when a common source point has propagated to spread widely person-to-person (e.g., zoonotic spread).