Pooled variance is a measure of the overall variance in multiple populations when the assumption of equal variance is not met. It is calculated by combining the sample variances of individual populations, weighted by their respective degrees of freedom. By estimating the overall variance, the pooled variance formula allows for more accurate hypothesis testing and statistical inference. It plays a crucial role in statistical analyses, such as t-tests and ANOVA, where comparing variances is essential for determining the significance of results.
