Central Limit Theorem
A statistical theorem stating that the sample mean of enough independent, identically distributed variables approximates a normal distribution regardless of the underlying shape.
Encyclopaedia
Explore comprehensive, evidence-informed explanations of key health economics concepts, including their development, application and relationships to other concepts. Published entries are validated through human expert review.
Chance Node
A point in a decision tree where the pathway followed is determined by probability rather than choice, branches summing to one.
Chi-Square Distribution
A continuous probability distribution arising from the sum of squared standard normal variables, underlying tests such as goodness of fit.
Choice Experiment
A stated preference method in which respondents repeatedly pick their preferred option from sets of hypothetical alternatives that vary across defined attributes.
Choice-Based Conjoint
A form of conjoint analysis in which respondents choose their preferred option from a set of alternatives rather than rating each one individually.
Cholesky Decomposition
A matrix factorisation technique decomposing a covariance matrix to generate correlated random samples from otherwise independently sampled parameters.
CLABSI Rate
A measure of the frequency of central line-associated bloodstream infections within a facility, tracking infection prevention performance for catheter care.
Clinical Benefit
A favourable effect of an intervention on how a patient feels, functions or survives relative to an appropriate comparator.
Clinical Benefit Rate
A cancer outcome measure combining complete response, partial response, and stable disease rates, giving a broader benefit picture than response rate alone.
Cluster Analysis
A statistical technique grouping individuals into subsets, called clusters, so members within a cluster are more similar to each other than to outsiders.
Cluster Randomization
A randomisation technique in which entire groups, such as clinics, rather than individuals, are randomly assigned to different treatment conditions.
Cohen's D
A standardised measure of effect size expressing the difference between two group means in units of their pooled standard deviation.
Cohort Design
An observational design following a group sharing a common starting characteristic forward in time to observe a subsequent outcome of interest.
Cohort Model
A decision-analytic model simulating the average experience of a defined group of patients moving through health states, rather than tracking each individually.
Cohort Simulation
The process of running a Markov model by tracking the proportion of a hypothetical cohort in each health state over cycles, not individual patients.
Cohort Trace
The complete record of the proportion of a modelled cohort occupying each health state at every cycle, produced by a Markov cohort model.
Coinsurance
A cost-sharing form in which an insured person pays a fixed percentage of a covered service's cost, with the insurer paying the rest.
Coinsurance Rate
The specific percentage of a covered service's cost an insured person is responsible for paying under a coinsurance arrangement.
Common Random Numbers
A variance reduction technique using the same sequence of random numbers across simulations of different alternatives, reducing the variance of their difference.
Communality
In factor analysis, the proportion of a variable's total variance explained by the underlying common factors, distinct from variance specific to it alone.