# Improve Quality Management – Statistics for Process Control

There are a number of management techniques which have been developed to improve quality management. Quality process control is based on using statistical analysis to calculate and forecast the performance of quality processes. One must have a basic understanding of statistics to appreciate the thinking that goes in to quality process control. Statistics is a quite threatening branch of mathematics that deals with variability. It is very complex and few people have command in the subject. However some of the thought that applies to quality process control can be explained easily enough without resorting to the mathematics. It is used to forecast and control of the performance of a system based on measurements of the output from the system.

The point about variability is that when you take a set of measurements will always get a bell-shaped, standard distribution curve. Any group of measurements exhibits variability which can be described in statistical expressions. Because of this we are able use statistical methods to monitor and control quality processes. We take samples from process and measure them, plotting and interpreting the resulting chart. This step allows seeing whether the process is under control or not. It provides indications about how problem can be fixed. Although statistical process control is frequently applied to production processes it can also be applied to other processes. The main thing is to measure the critical variables in the process and then to monitor them for signs of future troubles.

Proper tracking is done by a process control chart or graph. The graph shows how the output varies over time. The graph tells you whether the variability in process output is due to normal variation or whether there are any special causes responsible. To improve that process you should eliminate the special causes first, so that the variations are only due to the usual random factors.

Once the complete process is under control and the special causes have been eliminated, you can only make additional improvements by improving the whole process. The improvement target will either be to decrease the variation or to decrease the total value of the factor being measured. For a production process the target will be to tighten up on the tolerances so no defects are produced. These statistical process controls will help you to increase total quality management. Quality can be increased by other process controls too.