Epidemiology Study Designs - VET 401 Lecture 62

Comprehensive vocabulary flashcards covering experimental and observational epidemiological study designs, randomization, confounding, cohort studies, case-control studies, cross-sectional designs, and ecological studies.

Epidemiological Study

A measurement exercise undertaken to obtain estimates of epidemiological measures, such as disease frequency and risk associations within populations.

Observational Study

An epidemiological study design where the investigator does not assign exposure, but instead observes subjects and records their naturally occurring exposures and outcomes.

Experimental Study

A study design in which the investigator intervenes with the course of nature by actively assigning the exposure or treatment to the study subjects.

Randomized Controlled Trial (RCT)

An experimental study designed to evaluate an intervention where subjects are randomly allocated to treatment or control groups, often utilizing blinding to avoid bias.

Randomization

The process of randomly allocating subjects to study groups so that potential confounders are distributed evenly by chance, leaving treatment as the primary difference between groups.

Blinding (Masking)

A methodology in experimental trials where study personnel (and patients in human medicine) are kept unaware of group assignments to minimize observation and evaluation bias.

Confounder

An outside variable that influences both the exposure and the outcome, creating a false or distorted association between them.

Cross-Over Study

An experimental design where each subject serves as their own control by receiving both the exposure and control treatments at different times, requiring no carry-over effect and stability over time.

Cohort Study

An observational study design that starts with a group of disease-free individuals classified by exposure status and follows them over time to compare disease incidence between exposed and unexposed groups.

Prospective Cohort Study

A concurrent cohort study where the investigator selects subjects based on current exposure status and follows them forward into the future to monitor the development of outcomes.

Retrospective Cohort Study

A historical cohort study where the investigator reconstructs past exposures and subsequent disease outcomes of subjects from existing historical records.

Case-Control Study

An observational study design suited for rare diseases where subjects are selected based on whether they have the disease (cases) or do not (controls), and prior exposures are compared.

Cross-Sectional Study

An observational study that assesses exposure and outcome simultaneously in a population at a single point in time, making it difficult to establish whether exposure preceded the outcome.

Ecological Study

An observational study design where exposures and outcomes are measured and analyzed at the aggregate or group level (such as countries, states, or counties) rather than the individual level.

Ecological Fallacy (Ecological Bias)

The logical error or bias that occurs when inferences about individual-level associations are incorrectly deduced from aggregate, group-level associations.

Diagnostic Test Evaluation

A study design aimed at determining the clinical accuracy of a diagnostic assay by estimating its sensitivity and specificity.

James Lind's Scurvy Experiment

One of the earliest clinical trials, conducted aboard the Salisbury, where $12$ scurvy-affected sailors were assigned different treatments including citrus, cider, vinegar, sea water, and dilute sulphuric acid.

Trypanosoma cruzi

The protozoal parasite that causes Chagas disease in dogs and humans, transmitted by kissing bugs.

Triatoma Species

A genus of kissing bugs that serves as the vector for Trypanosoma cruzi, transmitting Chagas disease.

John Snow

The physician who investigated the 1850s London cholera outbreak, using observational deduction to trace clusters of cholera cases to sewage-polluted water from the Broad Street public pump.