Belief Bias
A form of faulty reasoning in which our expectations prevent us from seeing alternative explanations for our observations.
Epidemiology
The scientific study of the frequency, distribution, and causes of a particular disease or other health outcome in a population.
Descriptive Study
Research method in which researchers observe and record a participants' behaviors, often forming hypotheses that are later tested more systematically; includes case studies, interviews, and surveys.
Case Study
A descriptive study in which one person is studied in depth in the hope of revealing general principles.
Survey
A questionnaire used to ascertain the self-reported attitudes or behaviors of a group of people.
Observational Study
A nonexperimental research method in which a researcher observes and records the behavior of a research participant.
Correlation Coefficient
A statistical method of the strength and direction of the relationship between two variables, and thus how well one predicts the other.
Scatterplot
A graphed cluster of data points, each of which presents the values of two variables in a descriptive study.
Dependent Variable
The behavioral or mental process in an experiment that may change in response to manipulation of the independent variable; the variable that is being measured.
Random Assignment
Assigning research participants to groups by chance, thus minimizing preexisting differences among the groups.
Expectancy Effects
A form of bias in which the outcome of a study is influenced either by the researcher's expectations or by the study participant's expectations.
Double-Blind Study
A technique designed to prevent observer and participant expectancy effects in which neither the researcher nor the participants know the purpose of the study or which participants are in each condition.
Quasi-Experiment
A study comparing two groups that differ naturally on a specific variable of interest.
Cross-Sectional Study
A study comparing representative groups of people of various ages on a particular dependent variable.
Longitudinal Study
A study in which a single group of people is observed over a long span of time.
Heritability
The amount of variations in a trait among individuals that can be attributed to genes.
Morbidity
As a measure of health, the number of cases of a specific illness, injury, or disability in a given group of people at a given time.
Mortality
As a measure of health, the number of deaths due to a specific cause in a given group of people at a given time.
Incidence
The number of new causes of a disease of condition that occur in a specific population within a defined time interval.
Prevalence
The total number of diagnosed causes of a disease or condition that exist at a given time.
Etiology
The scientific study of the causes or origins of specific diseases.
Retrospective Study
A backward-looking study in which a group of people who have a certain disease or condition are compared with a group of people who are free of the disease or condition, for the purpose of identifying background risk factors that may have contributed to t
Prospective Study
A forward-looking longitudinal study that begins with a healthy group of subjects and follows the development of a particular disease in that sample.
Randomized Clinical Trial
A true experiment that tests the effects of one independent variable on individuals or group of individuals.
Meta-Analysis
A quantitative technique that combines the results of many studies examining the same effect or phenomenon
Relative Risk
A statistical indicator of the likelihood of a causal relationship between a particular health risk factor and a health outcome; computed as the ratio of the incidence (or prevalence) of a health condition in a group exposed to the risk factor to its inci