The table below gives data for the systolic blood pressure, in mm Hg, of 20 individuals who had systolic blood pressure between 145 and 165 mm Hg. Ten were given the experimental drug Angiocalm and ten were left untreated as a control. The initial report was 'The ratio of the largest to smallest variance of the groups did not exceed 4:1, so the data were analysed by a Model I single-factor ANOVA which showed Angiocalm significantly reduced systolic blood pressure compared to the control (F1,18 = 6.21, P = 0.023).' A physiologist who examined the results was concerned that the effect of Angiocalm appeared to be extremely variable among individuals and requested a Levene test on the data. Use a statistical package or the procedure in Section 14.7 to do this test. What can you conclude?
