Time series chart

Regular checks are intended to monitor whether the measures introduced have led to the desired improvements in the process flows and to guarantee that future deviations from the specified planned values will be detected in good time.

Process capability has proved to be a suitable means of verifying the performance and stability of a process. In PPM, you can display a history of the process capability, which you can use to demonstrate the (short-term) success of your Six Sigma project and, at the same time, to monitor the sustainability of the success with recurring evaluations and respond to even minor deviations.

To do this, create a time series chart for the Minitab® Cpk measure in PPM with the data for the period from January 2007 to December 2008.

The required data for the time series analysis is available to you if you carry out the operations described in steps 1 and 2 on a regular basis, e.g., once a month, for the required period.

Procedure

  1. Perform a process capability analysis using the runppmminitab command line program.

    Example

    runppmminitab -user system -password manager -client umg -favoritefolder "Demo Path SixSigma"

    See chapter Run Minitab® using the command line.

  2. Import the values of the Minitab® Cpk measure to PPM.

    See chapter Use a Minitab® measure in PPM.

  3. Define two planned values for the Cpk measure - Planned value 1 at 1.230 and Planned value 2 at 1.330.

    Assign the planned values to the Billing process type.

  4. Display a 2D line chart with the set values.

It can be clearly seen that the process capability has constantly increased since the introduction of the improvement measures and has been in the green range since around April 2007.

Example: Time series chart for monitoring process capability (Cpk)

sixsigma_control