Luotettavuusväli

Luotettavuusväli, also known as a confidence interval in English, is a statistical concept used to express the uncertainty associated with a sample statistic. When we estimate a population parameter, such as the mean, from a sample, our estimate is unlikely to be exactly equal to the true population value. A luotettavuusväli provides a range of values that is likely to contain the true population parameter with a certain degree of confidence.

The confidence level, typically expressed as a percentage (e.g., 95%), indicates the probability that the method used to construct the interval will produce an interval containing the true population parameter. For example, a 95% luotettavuusväli means that if we were to repeat the sampling process many times and construct a luotettavuusväli for each sample, approximately 95% of those intervals would contain the true population parameter.

The width of the luotettavuusväli is influenced by the sample size and the variability within the sample. Larger sample sizes and lower variability generally lead to narrower intervals, indicating a more precise estimate. Conversely, smaller sample sizes or higher variability result in wider intervals, reflecting greater uncertainty. Luotettavuusvälit are essential tools for interpreting statistical results and understanding the potential range of true population values.