Sources of Variation

Sources of variation can be categorized into two major categories. These are called common cause variation and special cause variation.

Common Cause Variation:

·        Present all the times in the process

·        Individually will have a minor effect

·        Collectively the variation can be added up leading to significant effect

Special Cause Variation:

·        Not always present in the process

·        Appear sporadically

·        Come from outside the process

·        Can have large or small affect on variation but typically have major impact

Strategy to address special cause:

·        Gather the data real time to signal the special causes quickly

·        Take immediate actions to reduce the damage

·        Investigate for the cause – Understand what is different

·        Plan for a long term solution

Strategies to address the common causes involves

·        Stratify – Identify the patterns in the way the data is clustered or do not clustered

·        Experiment – Make planned changes and learn from the effect

·        Disaggregate – Break the processes into small pieces and manage the pieces effectively

7 Step method of process improvement:

1.      Purpose

·         What are we trying to do?

·        What problem/gap is being addressed?

·        What is the impact?

·        What are the other reasons to fix this gap?

·        How to know things are better once improved?

·        What is your plan for this project?

2.      Current Situation

·        What is the history?

·        What are the symptoms of the problem?

·        Where do they appear?

·        What happens when the problem occurs?

·        Who is involved?

·        Can we draw the flowchart to depict the process?

3.      Cause Analysis

·        What are the causes for the symptoms?

·        Which can be verified using data?

·        What are the potential root causes?

4.      Solutions

·        What actions will address the root causes?

·        What criteria can be used to compare the solutions?

·        What are the pros and cons of each solution?

·        Which is the best? Which one will be selected?

·        How to test in a small scale? How to verify with data?

·        Which solution proved to be more effective?

·        What are the plans for full scale implementation?

5.      Results

·        How will the results meet the targets?

·        How well the plan executed?

·        How the results can be sustained in future?

6.      Standardization

·        What is the new standard method?

·        How will the users be trained?

·        What is in place to ensure the results are maintained?

·        How the results will be monitored?

·        What means are in place to foster ongoing improvements?

7.      Future plans

·        What is not addressed by this project?

·        What are the recommendations?

·        What is being learned from the project?

·        How the documentation will be finished?

·        What is the exit criterion to close the project?

·        Did we meet the exit criteria?