Run Chart: Creation, Analysis, & Rules

Run Chart Example

A run chart displays observed data as they evolve over time. Just a basic graph that displays data values in a time order. Can be useful for identifying trends or shifts in process but also allows you to test for randomness in the process.

A run chart can reveal shifts and trends, but not points out of control (A run chart does not have control limits; therefore, it cannot detect out of control conditions.) You can turn a run chart into a control chart by adding upper and lower control limits.

Use it to:

  • track improvements (and determine success)
  • display outputs to look for stability or instability


Run Chart Analysis

(These examples are from the wonderful download Developed by Richard Scoville, PhD. (

Testing a change with a run chart

  1. Plot the baseline
  2. Extend the median and begin the test
  3. Continue to plot data following the change
  4. Apply the rules
  5. If there was a signal, re-plot with new median
Testing a change with a run chart

Testing a change with a run chart

 Run Chart Decision Rules


Signals of an effective change:

  • Runs – Are there too many or too few for just common cause variation.
    • A run is a series of consecutive points that all lie on the same side of the line.
    • Ignore the points exactly on the line!
  • Clustering – too few runs.
  • Mixtures – too many runs.
  • Shift – 6 or more consecutive points above or below the median.
    • A general rule of thumb is when seven or eight values are in succession above or below the average of the group, a shift has occurred.
  • Trend – 5 or more consecutive increasing or decreasing points.
    • A basic rule of thumb is when a Run Chart exhibits seven or eight points successively up or down, then a trend is clearly present in the data.
  • Astronomical Point – A dramatically different value.
Run Chart Decision Rules

Run Chart Decision Rules

Run Chart Signals

Counting Runs

Counting Runs

How Many Runs?

Expected Runs Table


Shewhart’s tests for runs




2 comments… add one
  • Jacques de Kock

    Is there perhaps some SAS code that would create the graph in step 5 above. I see that the SAS support document refers to Shewhart Charts.

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