Question 9.7: In Example 9.4 (in Section 9.1), several measurements of the...

In Example 9.4 (in Section 9.1), several measurements of the maximum hourly concentrations (in μg/m³) of SO_2 were presented for each of four power plants, and it was concluded that the mean concentrations at the four plants were not all the same. The following output (from MINITAB) presents the Tukey-Krarner 95% simultaneous confidence intervals for mean concentrations at the four plants. Which pairs of plants, if any, can you conclude with 95% confidence to have differing means?

Tu key 95% Simultaneous Confidence Intervals

All Pairwise Comparisons

Individual confidence level 98.87%

1 subtracted from:

Lower    Center   Upper    – – – – -+- – – – – – – – -+- – – – – – – – – – – +- – – – – – – – -+- – – –

2        109 .4      385.3     661. 1                                   ( – – – – – – – – – * – – – – – – – – )

3         21.4         312.3     603.1                          (- – – – – – – – -*- – – – – – – – )

4        -94.6        170.9     436.4                  (- – – – – – – – -*- – – – – – – – )

– – – – – -+- – – – – – – – -+- – – – – – – – -+- – – – – – – – -+- – – –

-300                      0                    300                 600

2 subtracted from:

Lower    Center   Upper  – – – – -+- – – – – – – – -+- – – – – – – – – – – +- – – – – – – – -+- – – –

3        -348.9     -73.0      202.9          ( – – – – – – – – – * – – – – – – – – )

4        -463.4     -214.3     34.7    ( – – – – – – – – – * – – – – – – – – )

– – – – – -+- – – – – – – – -+- – – – – – – – -+- – – – – – – – -+- – – –

-300                      0                    300                 600

3 subtracted from :

Lower    Center   Upper  – – – – -+- – – – – – – – -+- – – – – – – – – – – +- – – – – – – – -+- – – –

4        -406.8    -141.3      124.1    ( – – – – – – – – – * – – – – – – – – )

– – – – – -+- – – – – – – – -+- – – – – – – – -+- – – – – – – – -+- – – –

-300                      0                    300                 600