| Excel Spreadsheet Templates for Quality Control, Control chart for percent defective. In all of the control charts, the basic idea is to sample from a continuous production process at equal intervals of time and record some quality characteristic. Common quality characteristics include the percent defective (P-CHART). If the process is under control, the quality characteristics should vary about the population mean in a random manner. If a sample mean falls outside the control limits, there is a very small probability that this happened due to randomness or chance alone and the process should be investigated
P-CHART is the most versatile and popular control chart. To use P-CHART, quality inspectors classify sample items into two groups: good or bad. This can mean defective or non-defective, conforming or non-conforming to specifications, acceptable or unacceptable, or other definitions in which there are only two categories of results.
Brookshire Cookware Corporation, a producer of pots and pans located in Brookshire , Texas , uses P-CHART worksheets to monitor the quality of component parts received from its Mexican suppliers. At the end of each business day, Brookshire faxes a copy of each P-CHART to its suppliers. This feedback helps maintain a good working relationship with suppliers and alerts them to potential problems.
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