Statistical Methods in Quality Control

Statistical Methods in Quality Control

1. Definition: the statistical method of controlling the quality of the product we are producing

2. Control Charts

   • To monitor, control and improve process performance over time by studying variation and its source
   • There are many types of control charts, The control charts that you or your team decide to use should be determined by the type of data that you have
   • Types of data: Variable & Attributes
     • Variables: Things we can measure. Such as length, weight, height, time, temperature.
       • mean and range charts fall under the variable category
       • X and R charts fall under the variable category
         • X bar charts to monitor the changes in the mean of a process
           • GRAPH
           • X bar formulas
             • k= number of sample means
         • R-bar charts to monitor the dispersion or variability of the process
     • Attributes: Things we can count- Such as Number or percent of defective items. A number of defects per item. Types of defects
       • p and c type charts fall under attribute category

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