Title: Confidence interval - Wikipedia
Headings: Confidence interval
Confidence interval
Contents
Conceptual basis
Introduction
Meaning and interpretation
Misunderstandings
History
Philosophical issues
Relationship with other statistical topics
Statistical hypothesis testing
Confidence region
Confidence band
Basic steps
Significance of t-tables and z-tables
Example
Statistical theory
Definition
Approximate confidence intervals
Desirable properties
Methods of derivation
Summary statistics
Likelihood theory
Estimating equations
Hypothesis testing
Bootstrapping
Examples
Medical examples
Theoretical example
Alternatives and critiques
Comparison to prediction intervals
Comparison to Bayesian interval estimates
Confidence intervals for proportions and related quantities
Counter-examples
Confidence procedure for uniform location
Confidence procedure for ω2
See also
Confidence interval for specific distributions
References
Bibliography
External links

Content: This gives a range of values for an unknown parameter (for example, a population mean). The interval has an associated confidence level that gives the probability with which the estimated interval will contain the true value of the parameter. The confidence level is chosen by the investigator. For a given estimation in a given sample, using a higher confidence level generates a wider (i.e., less precise) confidence interval. In general terms, a confidence interval for an unknown parameter is based on sampling the distribution of a corresponding estimator. This means that the confidence level represents the theoretical long-run frequency (i.e., the proportion) of confidence intervals that contain the true value of the unknown population parameter. In other words, 90% of confidence intervals computed at the 90% confidence level contain the parameter, 95% of confidence intervals computed at the 95% confidence level contain the parameter, 99% of confidence intervals computed at the 99% confidence level contain the parameter, etc. The confidence level is designated before examining the data. Most commonly, a 95% confidence level is used. However, other confidence levels, such as 90% or 99%, are sometimes used.