Interrelationship Digraph Source

This posting gives the background and source of the interrelationship digraph.   It differentiates this source from the ‘Seven major SPC Tools’ and the ‘Magnificent Seven’.

GOAL/QPC, an educational consulting company, noticed a new book proposing seven new QC tools.   This book (Mizuno, 1988) was eventually translated into English.  GOAL/QPC created the Memory Jogger Plus+ (Brassard, 1989) featuring these new tools.  They called these new tools the ‘Seven Management and Planning Tools’ to differentiate them from the ‘Seven Major SPC Tools’.   The Seven Management and Planning Tools are:

1. Affinity diagram
   
2. Interrelationship digraph
   
3. Tree diagram
   
4. Prioritization matrices
   
5. Matrix diagram
   
6. Process decision program chart (PDPC)
   
7. Activity network diagram
   

Montgomery (2005, page 148) identifies ‘Seven Major SPC Tools’.  He calls them the ‘Magnificent Seven’.  They are:

1. Histogram (3/25/2008 and 5/1/2008 postings) or stem-and-leaf plot
   
2. Check sheet
   
3. Pareto chart (2/25/2008 and 5/18/2008 postings)
   
4. Cause and effect diagram (2/28/2008 posting)
   
5. Defect concentration diagram
   
6. Scatter diagram (3/28/2008 posting)
   
7. Control chart (1/30/2008, 2/11/2008, 2/14/2008, and 4/1/2008 postings)
   

The implication is that we can perform SPC in most cases using these tools.

Earlier, Ishikawa (1985) identified ‘Seven Major TQM’ (Total Quality Management) tools.   They are:

1. Histogram
   
2. Flowchart
   
3. Pareto chart
   
4. Cause and effect diagram
   
5. Run charts and graphs
   
6. Scatter diagram
   
7. X-bar and R control charts
   

Ishikawa also felt that the above tools would support most TQM projects.

One could say that Montgomery replaced the ‘flowchart’ and ‘run charts and graphs’ with the ‘check sheet’ and ‘defect concentration diagram’.   Montgomery also generalized the X-bar and R control charts with all control charts.

References

1. Brassard, M. (1989). The Memory Jogger Plus+^â. Salem, NH, Goal/QPC.
2. Mizuno, S. (1988). Management for Quality Improvement: The Seven New QC Tools. Cambridge, Productivity Press.