The visibility standard index (VSI) is a measure of Denver air pollution that is reported each dayto theDenver Post. The index ranges from 0 (excellent air quality) to 200 (very bad air quality).During the winter months, when air pollution is higher, the index has a mean of about 90 (rated as fair) with a standard deviation of approximately 30. Suppose that for 15 days (during the winter), the following VSI measures were recorded each day. Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 VSI 80 115 100 90 15 10 53 75 80 110 165 160 120 140 195 a) Make a control chart for the VSI, and plot the above data on the control chart. Besure to include the horizontal lines on the control chart b) identify all out-of-control signals (above or below the mean) that you find in the control chart by type (Type I, II, or III)
The visibility standard index (VSI) is a measure of Denver air pollution that is reported each dayto theDenver Post. The index
Suppose that for 15 days (during the winter), the following VSI measures were recorded each day.
Day | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
VSI | 80 | 115 | 100 | 90 | 15 | 10 | 53 | 75 | 80 | 110 | 165 | 160 | 120 | 140 | 195 |
a) Make a control chart for the VSI, and plot the above data on the control chart. Besure to include the horizontal lines on the control chart
b) identify all out-of-control signals (above or below the mean) that you find in the control chart by type (Type I, II, or III)
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