1. A health insurance company operates a 24/7 nurse advice line and is concerned about long call wait times. A time study team collected observations for the advice line's ­answer time (in seconds) over a one-week period, and the results are displayed in the table below. Please use excel and show all work.

1. 1. Using the standard deviation approach, determine the 99.5 percent confidence limits for the advice line call answer times.
2. Construct an appropriate control chart for the days.
   
   
3. 2. Perform an up/down runs test. What do you conclude about the randomness of answer times?
   
   
4. 3. Perform a median run test. What do you conclude about the randomness of answer times?

 

Observations 1 2 3 34567 4 8 9 10 Mean Day 1 45.9 35.4 30.6 26.2 23.5 22.2 20.2 19.5 18.6 18.2 26.0 Day 2 9.4 11.2 19.8 17.2 14.4 13.2 12.1 11.4 11.4 11.2 13.1 Day 3 8.0 7.6 10.2 8.0 7.8 7.6 7.5 7.2 7.3 7.2 7.8 Day 4 6.2 21.2 26.8 30.7 20.3 23.4 21.3 20.2 18.5 18.8 20.7 Day 5 23.4 23.1 22.1 19.6 18.6 18.7 17.4 16.0 15.6 17.5 19.2 Day 6 7.9 12.4 9.6 13.5 14.7 12.1 8.5 16.1 10.1 8.0 11.3 Day 7 21.0 17.4 16.5 18.0 15.9 15.4 12.9 13.7 15.6 11.3 15.8