Lesson 7: Variables in Epidemiology & Descriptive Epidemiology

What is nominal level?

Mutually exclusive events

What is ordinal level?

Order relationship.

What are reversible and irreversible relationships?

If A causes B but not vice versa → irreversible.

What are precedent and subsequent variables?

Precedent = independent; subsequent = dependent.

What are determinant and stochastic relationships?

Determinant: whenever A occurs, B occurs. Stochastic: when A is present, B is likely to occur.

What does descriptive epidemiology measure?

Distribution and frequency of a disease using time, place, and person.

What does analytical epidemiology measure?

Association between factors; explains causes of disease.

What studies are typical for descriptive epidemiology?

Cross-sectional and descriptive studies.

What studies are typical for analytical epidemiology?

Cohort and case-control studies.

What are the objectives of descriptive epidemiology?

Identify proportion affected; determine proportion exposed.

Why is age important?

All health events vary with age; susceptibility and physiology also vary.

Why does sex matter?

Diseases occur with different frequency due to genetic, anatomical, and hormonal differences.

What is the relevance of race?

Represents a set of common heritable biological traits.

Why is place of birth relevant?

Immigrants retain lifestyle of origin country for some time.

How does socioeconomic level affect health?

Lower strata show higher mortality and more health problems

Why does civil status matter?

Married people have lower mortality.

How does nutritional status influence health?

Malnutrition increases risk and severity of infectious diseases.

What lifestyle habits affect health?

Tobacco, alcohol, drug use, physical activity, leisure.

What are secular trends?

Changes over long periods (20+ years).

What are seasonal variations?

Disease frequency movements within a year that recur.

What are cyclical fluctuations?

Oscillatory movements spanning several years.

What are unexpected variations?

Excess disease cases leading to explosive or prolonged epidemics.

What is the purpose of studying place?

Identifying the location of the epidemiological study.

What are limitations of place data?

Diagnostic criteria, reporting quality, completeness of vital statistics.

What is an endemic?

Regular presence of a disease in a specific area.

What is an outbreak?

Sudden increase of cases in a very specific area.

(Ebola)

What is an epidemic?

Unexpected increase of cases in a region.

(Influenza)

What is a pandemic?

Cases occur simultaneously on more than two continents.

(Covid)