Statistics > Confidence Intervals > 2-Population Variance Statistics > Confidence Intervals > 2-Population Variance This utility computes the confidence intervals for the ratio of two population variances (σ12 / σ22). The confidence intervals are calculated using the following formula: where s1 and s2 are the sample standard deviations of two population samples, FL is the lower critical value (inverse F probability distribution at α/2, where α is the significance level), and FR is the upper critical value (inverse F probability distribution at 1 - α/2). Dialog Inputs The sample data can be inputted in one of three ways: Samples in one column: The population labels of samples are in one column of the Datasheet, and the individual samples are in another column. Samples in two columns: The samples of the two population are in two separate columns. Summarized sample data: The sample size and standard deviation/variance of each sample are provided (instead of individual sample values). The confidence level must be between 0 and 1. For example, enter 0.95 for a 95% confidence level.