Statistical Quality Control

Quality Assurance management is a discipline of preventing mistakes or defects in designing or implementing products or services deliveries, and avoiding problems when delivering business solutions or services to customers.

Quality Assurance management is a discipline of preventing mistakes or defects in designing or implementing products or services deliveries, and avoiding problems when delivering business solutions or services to customers. 

Statistical quality control uses statistical methods to monitor and maintain the quality of products and services.

Methods of Statistical Quality Control: Acceptance sampling is used when deciding to accept or reject a group of parts based on the quality found in a sample. Statistical process control uses control charts to determine whether a process should be continued or adjusted to achieve the desired quality. Quality assurance (QA) processes use statistical methods to monitor and maintain the quality of products and services.

QA Processes and Practices: Acceptance sampling is used to decide whether to accept or reject a group of parts based on the quality found in a sample. Statistical process control uses control charts to determine whether a process should be continued or adjusted to achieve the desired quality. Statistical process control uses sampling and statistical methods to monitor the quality of an ongoing process, such as a production operation. 

A graphical display referred to as a control chart provides a basis for deciding whether the variation in the output of a process is due to common causes (randomly occurring variations) or to out-of-the-ordinary assignable causes. Whenever assignable causes are identified, a decision can be made to adjust the process to bring the output back to acceptable quality levels.

Control charts can be classified by the type of data they contain. For instance, an X-chart is leveraged in situations where a sample mean is used to measure the quality of the output. Quantitative data such as length, weight, and temperature can be monitored with a control chart. The chart corresponds to the mean of the process when the process is in control and producing output of acceptable quality. 

The vertical axis of the control chart identifies the scale of measurement for the variable of interest. The upper horizontal line of the control chart, referred to as the upper control limit, and the lower horizontal line, referred to as the lower control limit, are chosen so that when the process is in control there will be a high probability that the value of a sample mean fall between the two control limits. 

Standard practice is to set the control limits at three standard deviations above and below the process mean. The process can be sampled periodically. As each sample is selected, the value of the sample mean is plotted on the control chart. If the value of a sample mean is within the control limits, the process can be continued under the assumption that the quality standards are being maintained. If the value of the sample mean is outside the control limits, an out-of-control conclusion points to the need for corrective action to return the process to acceptable quality levels.

Quality Assurance management is a discipline of preventing mistakes or defects in designing or implementing products or services deliveries, and avoiding problems when delivering business solutions or services to customers.

Posted in: Business Process Management,Information/Data Management,Quality