{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chap010st - Chapter 10 Quality Control CHAPTER 10 QUALITY...

Info icon This preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 10 - Quality Control CHAPTER 10: QUALITY CONTROL Answers to Discussion and Review Questions 1. The elements in the control process are: a. Define b. Measure c. Compare to standard d. Evaluate e. Take corrective action if needed f. Evaluate corrective action to insure it is working 2. Control charts are based on the premise that a process which is stable will reflect randomness: statistics of samples taken from the process (means, number of defects, etc.) will conform to a sampling distribution with known characteristics, so that statistical significance tests can be performed on sample statistics; and successive samples will not reveal any patterns which will enable prediction of future values other than specification of range of variability. 3. Control charts are used to judge whether the sample data reflects a change in the parameters (e.g., mean) of the process. This involves a yes/no decision and not an estimation of process parameters. 4. Order of observation of process output is necessary if patterns (e.g., trends, cycles) in the output are to be detected. 5. a. x chart—A control chart used to monitor process variables by focusing on the central tendency of a process. b. Range control charts are used to monitor process variables, focusing on the dispersion of a process. c. p-chart—is a control chart for attributes, used to monitor the proportion of defectives in a process. d. c-chart—is a control chart for attributes, used to monitor the number of defects per unit. 6. A run is a sequence of observations with a given characteristic. Run tests are helpful in detecting patterns in time series (e.g., control chart) data. 7. All points can be within control limits but with certain patterns developing in the data which would suggest the output is not random, and hence, not in control for long. 8. It is usually desirable to use both an up/down and a median run test on a given set of data because the tests are sensitive to different things. For example, one test can be more sensitive to trend and the other to bias. 9. No, there is always the possibility of a Beta or Type II error which is the probability of calling something random when in fact it is non-random or concluding that non- randomness is not present, when it actually is. 10-1
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Chapter 10 - Quality Control 10. Specifications are limits on the range of variation of output which are set by design (e.g., engineering, customers). Control limits are statistical bounds on a sampling distribution. They indicate the extent to which summary values such as sample means or sample ranges will tend to vary solely on a chance basis. Process variability refers to the inherent variability of a process the extent to which the output of a process will tend to vary due to chance. Control limits are a function of process variability as well as sample size and confidence level. Both are essentially independent of tolerances.
Image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern