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Unformatted text preview: MGT 364 - Fall 2004 Study Guide Chapters 6s, 7, 7s, 8 & 9 Exam 2 Chapter 6s (14 - 17 questions & 7 problems) 1. What does it mean if youre mean (0) is outside your control limits? If something is above or below the control limit, then they are said to be out of control and an assignable cause exist. *It is possible to be in control and not meet customer specifications *It is possible to be out of control and meet customer specifications 2. What does it mean to be in control and out-of-control? We use statistical process control to measure performance of a process. A process is said to be operating in statistical control when the only source of variation is common (natural) causes. The process must first be brought into statistical control by detecting and eliminating special (assignable) causes of variation. Then its performance is predictable, and its ability to meet customer expectations can be assessed. The objective of a process control system is to provide a statistical signal when assignable causes of variation are present. When the average of the samples falls within the upper and lower control limits and no discernible pattern is present, the process is said to be in control with only natural variation present. 3. What is a range? Measure of dispersion. The range is defined as the difference between the largest and smallest items in one sample. 4. Control chart limits are based on individual, small, or large samples? ?Average? 5. What is an assignable cause? Assignable Variations : in a process can be traced to a specific reason. Factors such as machine wear, misadjusted equipment, fatigued or untrained workers, or new batches of raw material are all potential sources of assignable variations. Natural and assignable variations distinguish two tasks for the operations manager. 1) To ensure that the process is capable of operating under control with only natural variation. 2) To identify and eliminate assignable variations so that the processes will remain under control. 6. What is a measure of central tendency? The theoretical foundation for x-bar charts is the central limit theorem. This theorem states that regardless of the distribution of the population, the distribution of x-bars (each of which is a mean of a sample drawn from the population) will tend to follow a normal curve as the number of samples increases. The theorem also states that : (1) the mean of the distribution of the x-bars (called x-double bar) will equal the mean of the overall population (called ); and (2) the standard deviation of the sampling distribution, x-bar , will be the popular standard deviation, , divided by the square root of the sample size, n ....
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This note was uploaded on 03/24/2010 for the course MGT 364 taught by Professor Staff during the Spring '08 term at Missouri State University-Springfield.
- Spring '08