The confidence interval around a particular value gives an estimated range around the measured value that is likely to include the true (population) value of the parameter. Confidence intervals are usually estimated from a given set of sample data: their magnitude depends on the inherent variability of the parameter in the population as well as the size of the sample taken (they are closely related to the standard error). If independent samples are taken repeatedly from the same population then a certain percentage (the confidence level) of intervals will contain the true value of the parameter. Most commonly 95% confidence intervals are reported (the true population value will lie in the confidence interval in 95/100 samples), although 99% and 90% are also used. In economic modelling confidence intervals are used to define plausible ranges for values of many input parameters.

How to cite: Confidence Interval [online]. (2016). York; York Health Economics Consortium; 2016.

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