The following table shows the vital capacity measurements of 60 adult males classified by occupation and age group:

Occupation Age Group A B C D 1 4.31 4.68 4.17 5.75 4.89 6.18 3.77 5.70 4.05 4.48 5.20 5.53 4.44 4.23 5.28 5.97 4.59 5.92 4.44 5.52 2 4.13 3.41 3.89 4.58 4.61 3.64 3.64 5.21 3.91 3.32 4.18 5.50 4.52 3.51 4.48 5.18 4.43 3.75 4.27 4.15 3 3.79 4.63 5.81 6.89 4.17 4.59 5.20 6.18 4.47 4.90 5.34 6.21 4.35 5.31 5.94 7.56 3.59 4.81 5.56 6.73 Test for differences among occupations, for differences among age groups, and for interaction.
Let a ¼ :05 for all tests.