Carcinogenesis: the process by which normal cells are transformed into cancer cells.

Case-control study: the epidemiologic observation of a group of persons with a disease of interest and a group of persons without the disease; cases and controls are compared for the frequency of the factor that is believed to be associated with the disease.

Causality: the relationship between an event (e.g., an exposure) and a second event (e.g., the disease) in which the second event is explained as a consequence of the first.

Census: the enumeration of an entire population that includes demographic information.

Census tract: a geographic area for which details on population structure are tabulated at a given census. Census tracts typically contain 1,200 to 8,000 people (with a target of 4,000 people).

Centroid: the geographic or population center for a geographic unit.

Classification of diseases: arrangement of diseases into categories based on shared characteristics such as body site that they occur, etiology, histology, and others.

Cluster: a grouping of health related events that are related in time, space, or both.

Cohort study: the epidemiologic observation of a group of persons with the exposure hypothesized to be associated with a disease of interest and a group of persons without the exposure; exposed and unexposed persons are often followed with time until the disease of interest develops and the frequency of disease occurrence by exposure is calculated.

Cold shutdown: a state of a nuclear reactor in which it is deemed subcritical and its coolant system is at atmospheric pressure and at a temperature less than 200 °F.

Confounder: a variable that is associated with both an exposure of interest and disease of interest and may result in statistically false cause or prevent detection of a cause-effect relationship between the exposure and outcome of interest.

Confidence intervals: the computed range with a particular confidence level, commonly set up at 95 percent, intended to give the assurance that if a statistical model is correct, the true value of the parameter (for example risk estimation) is within the range indicated; if the 95% CI range does not include 1, then the estimated risk is significantly different from that of a comparison group.

Correlation: a statistical measurement of the relationship between two variables. Correlation can be positive (as one variable goes up, the other variable goes up), or negative (as one variable goes up, the other variable goes down).



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