Contingency table - A contingency table organizes observations by combinations of categorical variables.
Continuity correction - A continuity correction adjusts a boundary when a continuous distribution approximates a discrete one.
Continuous probability distribution - A continuous probability distribution describes uncertainty in a quantity whose probability is spread across a continuum, rather than concentrated on...
Continuous random variable - A continuous random variable represents an uncertain numerical quantity through a distribution that assigns zero probability to each individual value.
Contrast - In statistics, a contrast is a linear comparison of means whose coefficients sum to zero.
Control chart - A control chart is a statistical monitoring display that plots a process measure over time or successive samples against a reference center and control limits.
Control factor - A control factor is an input or design choice whose level can be deliberately set in an experiment or operating process.
Control function (econometrics) - In econometrics, a control function is a modeled term added to an outcome equation to account for dependence between an explanatory variable and unobserved...
Control group - A control group is the comparison group used to assess the outcome of an intervention or experimental condition.
Control limits - Control limits are statistical reference boundaries used in a control chart to identify observations or patterns that warrant investigation under an assumed...
Control variates - Control variates are a variance-reduction technique that uses a correlated quantity with a known expected value to improve a Monte Carlo estimate.
Controlling for a variable - Controlling for a variable means accounting for it when making a statistical comparison or estimating a relationship.
Convenience sample - A convenience sample is a sample selected because its members are easy to reach or readily available, rather than through a probability sampling design with...
Cook's D - Cook's D, also called Cook's distance, measures how strongly one observation influences a fitted regression model.
Correct sampling - Correct sampling is a technical principle in Pierre Gy's theory of sampling for particulate materials: every constituent particle of the lot should have an...
Correlation - Correlation describes a statistical association between variables, often summarized by a coefficient indicating its direction and strength.
Correlation coefficient - A correlation coefficient is a numerical summary of the direction and strength of a specified association between variables.
Correlation does not imply causation - Correlation does not imply causation means that an observed statistical association, by itself, does not establish that changing one variable would change...
Correlation function - A correlation function describes how a statistical relationship varies across pairs of times, locations, or other index values.
Correlation matrix - A correlation matrix is a square table containing the pairwise correlation coefficients among a set of variables.
Correlational measures - Correlational measures are statistics that summarize the degree and, where defined, direction of association between variables.
Count data - Count data record how many events, objects, or observations occur within a defined unit, category, period, or amount of exposure.
Counterbalancing - Counterbalancing is the planned distribution of condition orders across participants or trials to reduce confounding between experimental conditions and...
Counternull - A counternull is a nonnull effect value that has the same evidential standing as a specified null value under a stated statistical procedure, commonly...
Covariance - Covariance measures how two variables vary together relative to their respective means.
Covariance function - A covariance function specifies the covariance between a random process's values at two inputs.
Covariance matrix - A covariance matrix is a square table describing the variances and pairwise covariances of a random vector's components.
Cox model - The Cox model usually means Cox proportional hazards regression, a method relating predictors to the time until an event while accommodating appropriate...
Cramér's phi ( F c ) - Cramér's phi, commonly written phi_c and more widely known as Cramér's V, measures association between two categorical variables in a contingency table.
Criterion variable - A criterion variable is the variable a statistical model or prediction study aims to predict.
Critical value - A critical value is a boundary used in a statistical decision rule, commonly separating rejection and nonrejection regions for a hypothesis test.
Cromwell's rule - Cromwell's rule is advice to avoid assigning exact prior probabilities of zero or one to uncertain empirical propositions.
Cross-correlation matrix - A cross-correlation matrix describes pairwise relationships between components of two random vectors.
Cross-entropy - Cross-entropy is the expected negative logarithm of probabilities assigned by one distribution to outcomes generated by another.
Cross-entropy loss - Cross-entropy loss is a training objective that penalizes a model for assigning low probability to the correct outcome.
Cross-sectional regression - Cross-sectional regression models relationships between an outcome and explanatory variables across different units observed for a common point or period in...
Crossover study - A crossover study compares interventions by having the same participants receive different interventions during successive periods.
Cumulative distribution - A cumulative distribution describes how probability accumulates up to each value of a variable.
Cumulative distribution function - The cumulative distribution function, or CDF, of a real-valued random variable X is F(x) = P(X <= x).
Cumulative incidence - Cumulative incidence is the probability that a specified event has occurred by a particular time.
Curvilinear relationship - A curvilinear relationship is a relationship between variables that is better represented by a curve than by a straight line on the chosen measurement scales.
Cusum chart - A CUSUM chart, short for cumulative sum control chart, monitors a process by accumulating evidence of departures from a reference level.
Cut-off sampling - Cut-off sampling is a sampling procedure that deliberately excludes part of a target population from possible selection using a threshold or related...
Cuzick - Edwards test - The Cuzick - Edwards test is a statistical test for spatial clustering of cases relative to a comparison population represented by controls.
Cyclical effect - A cyclical effect is a recurring rise and fall in a time series.
Data assimilation - Data assimilation is the process of combining observations with a model-based estimate to infer the state of a changing system.
Data collection - Data collection is the planned process of obtaining and recording observations or measurements for a defined purpose.