Run Chart

Run Chart is a plot of a metric performance with respect to time. It is used to check for presence of special causes in the process or in other words to determine whether the process is random or not (as a perfectly random process will not have any special causes). A Run Chart checks for four types of special causes - Trends, Oscillations, Clusters and Mixtures.

Trends - Sustained drift in the metric performance either upwards or downwards.

Oscillations - Continuous fluctuations in the metric performance indicating that a process is not steady.

Clusters - Group of metric performance readings in one area of chart or continuous readings of metric performance within a short range.

Mixtures - Continuous crossing of the mean or the center line (in subsequent metric performance readings) usually indicating that process is operating at different levels.

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Run Charts vs Control Charts

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November 20, 20187 yr

Q. 111 Explain the four terms with respect to Run Charts - Mixtures, Clusters, Oscillations and Trends. Does a run chart provide any advantage as compared to a control chart?

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November 23, 20187 yr

A run chart is a line graph of data plotted over time. By collecting and charting data over time one can find trends or patterns in the process. They can show how the process is running however as they do not use control limits hence they cannot tell if a process is stable.

There are four basic patterns of no randomness that a run chart can detect—mixture, cluster, oscillating, and trend patterns.

A mixture is characterized by an absence of points near the center line:

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