ECONOMICS|economic analysis|statistics
- cairt cóimheastóra Reference Faomhadh an téarma seo mar chuid de Thionscadal Lex
- ga
- control chart
- en
- Definition graph used to study how a process changes over time Reference ASQ. Control Chart, http://asq.org/learn-about-quality/data-collection-analysis-tools/overview/control-chart.html [21.10.2014]
- Comment Data are plotted in time order. A control chart always has a central line for the average, an upper line for the upper control limit and a lower line for the lower control limit. These lines are determined from historical data. By comparing current data to these lines, you can draw conclusions about whether the process variation is consistent (in control) or is unpredictable (out of control, affected by special causes of variation).Control charts for variable data are used in pairs. The top chart monitors the average, or the centering of the distribution of data from the process. The bottom chart monitors the range, or the width of the distribution. If your data were shots in target practice, the average is where the shots are clustering, and the range is how tightly they are clustered. Control charts for attribute data are used singly.