Provides answers to commonly asked questions about COBRA. Health Benefits Under the Consolidated Omnibus Budget Reconciliation Act (COBRA) (PDF) Provides a detailed overview of the major provisions of COBRA.
In the two-sample pooled t-test the pooled variance is computed by averaging the two individual sample variances. The assumptions for the two-sample pooled t-test for the difference in two means are that there are random samples from two independent normal populations with common but unknown variance.
The t statistic to test whether the population means are different is calculated as: where. Here s 2 is the unbiased estimator of the variance of the two samples, ni = number of participants in group i, i =1 or 2. Note that in this case is not a pooled variance.