Statistics for Business and Economics (13th Edition)
Statistics for Business and Economics (13th Edition)
13th Edition
ISBN: 9780134506593
Author: James T. McClave, P. George Benson, Terry Sincich
Publisher: PEARSON
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Chapter 13, Problem 13.90ACI

Defects in graphite shafts. Over the last year, a company that manufactures golf clubs has received numerous com- plaints about the performance of its graphite shafts and has lost several market share percentage points. In response, the company decided to monitor its shaft production process to identify new opportunities to improve its product. The process involves pultrusion. A fabric is pulled through a thermosetting polymer bath and then through a long heated steel die. As it moves through the die, the shaft is cured. Finally, it is cut to the desired length. Defects that can occur during the process are internal voids, broken strands, gaps between successive layers, and microcracks caused by improper curing. The company’s newly formed quality department sampled 10 consecutive shafts every 30 minutes, and nondestructive testing was used to seek

Shift Number Number of Defective Shafts Proportion of Defective Shafts
1 9 .05625
2 6 .03750
3 8 .05000
4 14 .08750
5 7 .04375
6 5 .03125
7 7 .04375
8 9 .05625
9 5 .03125
10 9 .05625
11 1 .00625
12 7 .04375
13 9 .05625
14 14 .08750
15 7 .04375
16 8 .05000
17 4 .02500
18 10 .06250
19 6 .03750
20 12 .07500
21 8 .05000
22 5 .03125
23 9 .05625
24 15 .09375
25 6 .03750
26 8 .05000
27 4 .02500
28 7 .04375
29 2 .01250
30 6 .03750
31 9 .05625
32 11 .06875
33 8 .05000
34 9 .05625
35 7 .04375
36 8 .05000

Source: W. Kolarik. Creating Quality: Concepts. Systems, Strategies, and Tools. Copyright © 1995 by William J. Kolarik. Used by permission of William j. Kolarik.

out flaws in the shafts. The data from each 8-hour work shift were combined to form a shift sample of 160 shafts. Data on the proportion of defective shafts for 36 shift samples are presented in the table shown at the bottom of the previous column.

  1. a. Use the appropriate control chart to determine whether the process proportion remains stable over time.
  2. b. Does your control chart indicate that both common and special causes of variation are present? Explain.
  3. c. Data on the types of flaws identified are given in the table below. [Note: Each defective shaft may have more than one flaw.] To help diagnose the causes of variation in process output, construct a Pareto diagram for the types of shaft defects observed. Which are the “vital few”? The “trivial many"?
Type of Defect Number of Defects
Internal voids 11
Broken strands 96
Gaps between layer 72
Microcracks 150
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Chapter 13 Solutions

Statistics for Business and Economics (13th Edition)

Ch. 13.4 - The data in the following table were collected for...Ch. 13.4 - Prob. 13.12ACBCh. 13.4 - Active pharmaceutical ingredient. During the...Ch. 13.4 - Detecting gender-related employment disparities....Ch. 13.4 - Pain levels of ICU patients. Various interventions...Ch. 13.4 - Quality control for irrigation data. Most farmers...Ch. 13.4 - Improving public health waiting times. Statistical...Ch. 13.4 - Cereal box manufacturing. A machine at K-Company...Ch. 13.4 - Detecting under-reported emissions. The...Ch. 13.4 - 13 20 Selecting the best wafer-slicing machine....Ch. 13.4 - Chunky data. BPI Consulting, a leading provider of...Ch. 13.4 - Military aircraft bolts. A precision parts...Ch. 13.5 - What characteristic of a process is an R-chart...Ch. 13.5 - Prob. 13.24LMCh. 13.5 - Use Table IX on page 13-74 to find the values of...Ch. 13.5 - Construct and interpret an R-chart for the data in...Ch. 13.5 - Construct and interpret an R-chart for the data in...Ch. 13.5 - Construct and interpret an R-chart and an x -chart...Ch. 13.5 - Weight of packed frozen scallops. In Quality...Ch. 13.5 - Detecting gender-related employment disparities....Ch. 13.5 - Pain levels of ICU patients. Refer to the Research...Ch. 13.5 - Quality control for irrigation data. Refer to...Ch. 13.5 - Lowering the thickness of an expensive blow-molded...Ch. 13.5 - Cola bottle filling process. A soft-drink bottling...Ch. 13.5 - Chunky data. Refer to Exercise 13.21e (p. 13-40)...Ch. 13.5 - Replacement times for lost ATM cards. In an effort...Ch. 13.5 - Military aircraft bolts. Refer to the...Ch. 13.5 - Precision of scale weight measurements. The...Ch. 13.6 - What characteristic of a process is a p-chart...Ch. 13.6 - In each of the following cases, use the sample...Ch. 13.6 - The proportion of defective items generated by a...Ch. 13.6 - To construct a p-chart for a manufacturing...Ch. 13.6 - To construct a p-chart, 20 samples of size 150...Ch. 13.6 - Academic failure rates in Nigeria. The quality...Ch. 13.6 - Monitoring surgery complications. An article on...Ch. 13.6 - Rental car call center study. A worldwide rental...Ch. 13.6 - Defective micron chips. A manufacturer produces...Ch. 13.6 - Hand break cable defects. In Control Engineering...Ch. 13.6 - Monitoring newspaper typesetters. Accurate...Ch. 13.6 - Quality of rewritable CDs. A Japanese compact disc...Ch. 13.6 - Leaky process pumps. Quality (February 2008)...Ch. 13.6 - Rubber company lire tests. Goodstone Tire Rubber...Ch. 13.7 - Explain why it is inappropriate to conduct a...Ch. 13.7 - Explain the difference between process spread and...Ch. 13.7 - Describe two different ways to assess the...Ch. 13.7 - Why is it recommended to use and interpret Cp in...Ch. 13.7 - For a process that is in control and follows a...Ch. 13.7 - Find the specification spread for each of the...Ch. 13.7 - Find (or estimate) the process spread for each of...Ch. 13.7 - Find the value of Cp for each of the following...Ch. 13.7 - Upper specification limit of a process. An...Ch. 13.7 - Capability of an in-control process. A process is...Ch. 13.7 - Water use at a thermal power plant. Thermal power...Ch. 13.7 - Cereal box filling process. Refer to the data on...Ch. 13.7 - Military aircraft bolts. Refer to Exercise 13.22...Ch. 13.7 - Bioreactor production of antibodies. Benchtop...Ch. 13.7 - Driver gear bore holes. During the manufacture of...Ch. 13.7 - Lowering the thickness of an expensive blow-molded...Ch. 13 - Define quality and list its important dimensions.Ch. 13 - What is a process? Give an example of an...Ch. 13 - What is a system? Give an example of a system with...Ch. 13 - Describe the six major sources of process...Ch. 13 - Suppose all the output of a process over the last...Ch. 13 - Processes that are in control are predictable;...Ch. 13 - Compare and contrast special and common causes...Ch. 13 - Explain the difference between control limits and...Ch. 13 - Should control charts be used to monitor a process...Ch. 13 - Under what circumstances is it appropriate to use...Ch. 13 - A process is under control and follows a normal...Ch. 13 - Weight of a product. Consider the time series data...Ch. 13 - Lengths of pencils. The length measurements of 20...Ch. 13 - Applying pattern-analysis rules. Use the...Ch. 13 - Defective plastic mold. A company that...Ch. 13 - Robotics clamp gap width. Control chart...Ch. 13 - Package sorting time. AirExpress. an overnight...Ch. 13 - Waiting times of airline passengers. Officials at...Ch. 13 - Defects in graphite shafts. Over the last year, a...Ch. 13 - New iron-making process. Mining Engineering...Ch. 13 - CPU of a computer chip. The central processing...Ch. 13 - Bayfield Mud Company case. The text Quantitative...
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