EXAMPLE : In a study of the effect of glucose on insulin release, 12 identical specimens of pancreatic tissue were divided into three groups of four specimens each. Three levels (Low, Medium, High) of glucose concentration were randomly assigned to the three groups and each specimen with a group was treated with its assigned level of glucose. Given below are the amounts of insulin released by the tissue specimens. Does the data indicate that there is a difference in the three concentrations of glucose? Note that in this example, twelve specimens were randomly divided into three groups and we did something to the items The resulting groups of observations for each glucose concentration are treated as independent random sample from three different populations. EXAMPLE : Given below are heart volume measurements taken on male athletes. Do heart volumes differ for male athletes who participate in different sports?