722 CHAPTER 14 Statistical Process Control Big (or Very Large) Data Project Refer to Data Set 46 “Dow Jones Industrial Average” in Appendix B. This data set includes opening values, high values, low values, and closing values for each day from May 27, 1896 to December 28, 2018, and there are records for 31,784 days. Use the closing values to construct a run chart, and comment on the result. Hint: For a technology that does not include a function for generating a run chart, create a new column of consecutive integers from 1 to 31,784, then construct a scatterplot using the consecutive integers for x (horizontal scale) and use the closing values for y (vertical scale). FROM DATA TO DECISION Critical Thinking: Are the axial loads within statistical control? Is the process of manufacturing cans proceeding as it should? Exercises 5–8 in Section 14-1 used process data from the manufacture of 0.0109-in.-thick aluminum cans. Refer to Data Set 41 “Aluminum Cans” in Appendix B and conduct an analysis of the process data for the cans that are 0.0111 in. thick. The values in the data set are the measured axial loads of cans, and the top lids are pressed into place with pressures that vary between 158 lb and 165 lb. The 175 axial loads are in one column, the first 7 are from the first day, the next 7 are from the second day, and so on, so that the “subgroup size” is 7. Analyzing the Results Based on the given process data, should the company take any corrective action? Write a report summarizing your conclusions. Address not only the issue of statistical stability but also the ability of the cans to withstand the pressures applied when the top lids are pressed into place. Also compare the behavior of the 0.0111-in. cans to the behavior of the 0.0109-in. cans, and recommend which thickness should be used. Cooperative Group Activities 1. Out-of-class activity Collect your own process data and analyze them using the methods of this chapter. It would be ideal to collect data from a real manufacturing process, but that might be difficult. Instead, consider using a simulation or referring to published data. Obtain a copy of computer results and write a brief report summarizing your conclusions. Here are some suggestions: • Shoot five basketball foul shots (or shoot five crumpled sheets of paper into a wastebasket) and record the number of shots made; then repeat this procedure 20 times. Use a p chart to test for statistical stability in the proportion of shots made. • Measure your pulse rate by counting the number of times your heart beats in 1 min. Measure your pulse rate four times each hour for several hours, then construct appropriate control charts. What factors contribute to random variation? Assignable variation? • Search the Internet and record the closing of the Dow Jones Industrial Average (DJIA) for each business day of the past 12 weeks. Use run and control charts to explore the statistical stability of the DJIA. Identify at least one practical consequence of having this process statistically stable, and identify at least one practical consequence of having this process out of statistical control.
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