Five Whys

Systems Thinking technique (from Toyota) of investigating every defect/surprise to understand Root Causes, and to plan appropriate investments to prevent recurrence.

• cf retrospective

Eric Ries: http://startuplessonslearned.blogspot.com/2008/11/five-whys.html

• and this
• Jon Miller's critique of Eric's Lean Startup book has a long section challenging Eric's version of 5whys.

http://en.wikipedia.org/wiki/5_Whys

Joel Spolsky http://www.joelonsoftware.com/items/2008/01/22.html

http://software.isixsigma.com/library/content/c020610a.asp

visual structure

• Ishikawa Diagram (Fishbone Diagram) This shows why it's not 1*5 nodes, but 3^5 ("243 Whys" would be a harder sell)
  • even worse, in a complex system there is no Root Cause (see Systemantics)
• Diagram Of Effects (including loops!)
• MsExcel table http://www.bulsuk.com/2009/07/5-why-analysis-using-table.html

can also be more general process of challenging assumptions to going to a Meta Level: see Kathy Sierra 2007-03-21-SierraMetaLevel