In statistical analysis, sampling techniques are used to provide an estimate of some aspect of a particular population, for example the average age. This avoids having to take a census of the entire population. Because the estimate is based on a sample and not the entire population, the estimate is subject to error. A confidence interval provides a range of values about the estimate within which the true value (the value of the parameter based on the entire population) lies. The smaller the confidence interval, the more precise the statistical estimate.