Management

For lesson 11, you will complete EWMA Chart exercise in the exercise folder in lesson 11 folder. In the folder you will find the exercise sheet that provides you directions to open the worksheet and create the charts needed and provide the information to answer the questions. For those of you with Minitab, this will also be good for you to learn your way around Minitab, for those of you who do not have Minitab; I have placed the results (the window and the graph outputs) in the exercise folder. You will be able to answer the questions on the exercise sheet with this. Once you have completed the exercise, post it in the drop box for lesson 11 ... Here is the book description. CourseText:Montgomery,Douglas C.INTRODUCTIONTOSTATISTICALQUA ... Here is the book description. CourseText:Montgomery,Douglas C.INTRODUCTIONTOSTATISTICALQUALITYCONTROL,JohnWiley&Sons,7thEdition An EWMA chart consists of the following: • EWMA points, which are exponentially-weighted moving averages. Each EWMA point incorporates information from all of the previous subgroups or observations, but gives less weight to process data as they get older. • Center line (green), which is the overall average of the exponentially-weighted moving average. • Control limits , which are located, by default, 3  (standard deviations ) from the center line, provide a visual means for assessing whether the process is in control . Points located beyond the control limits signal an out-of-control condition. Examine the EWMA chart for data points located beyond the upper or lower control limits. Points located beyond the control limits are indicators that the process is out of control. You should then initiate a search for potential causes for the special-cause variation. EWMA - means Exponentially Weighted Moving Average. Each EWMA point incorporates information from all the previous subgroups or observations. Each subgroup or observation value is weighted based on its age; older values are weighted less while newer values are weighted more. Center line - A horizontal reference line that is the expected value for the statistics of the quality characteristic being charted. Used to estimate the process location or process center. Control limits - Horizontal reference lines located above and below the center line; used to judge whether there is evidence that the process is out of control. Standard deviation - The most common measure of variation (or spread). The standard deviation is approximately the average deviation of each observation from the mean. Control (also, in control) - The absence of special-cause variation. A process that is in control exhibits only random variation. In other words, the process is stable or consistent. Control charts assess statistical control by determining whether the process output falls within statistically calculated control limits and exhibits only random variation. Out of control - A process is out of control when it has a nonrandom pattern of variability that may be due to the presence of special causes. Special-cause variation - An unusual pattern of variability that demonstrates occurrences that are not normally part of a process. Assignable cause, controlled, and nonrandom variation are other terms used to describe special-cause variation.