Question: A study of chronic lung disease reported the forced expiratory volumes in one second (FEV₁s) for three groups of patients: nine patients with a tracheostomy and lung disease (Group 1), 10 patients with parenchymal lung disease but no tracheostomy (Group 2), and five patients with tracheostomy but no clinical obvious lung disease (Group 3) {Fletcher EC, Schaaf JW, Miller J, et al.: Long-term cardiopulmonary sequelae in patients with sleep apnea and chronic lung disease. American Review of Respiratory Diseases 1987;135:525-533.}. The data are in the following table. Determine if there is a difference in the population means and then use Tukey’s HSD and Fisher’s LSD for significant differences between the individual pairs of means. Let a = 0.05.