5 whys and 5 hows

What It Is

•The five whys and five hows constitute a questioning process designed to drill down into the details of a problem or a solution and peel away the layers of symptoms.
•The technique was originally developed by Sakichi Toyoda. He states “that by repeating why five times, the nature of the problem as well as its solution becomes clear.”
•The five whys are used for drilling down into a problem and the five hows are used to develop the details of a solution to a problem.
•Both are designed to bring clarity and refinement to a problem statement or a potential solution and get to the root cause or root solution.
•Edward Hodnet, a British poet, observed, “If you don’t ask the right questions, you don’t get the right answers. A question asked in the right way often points to its own answer. Asking questions is the ABC of diagnosis. Only the inquiring mind solves problems.”

When to Use It

•When we want to push a team investigating a problem to delve into more details of the root causes, the five whys can be used with brainstorming or the cause-and-effect diagram.
•The five hows can be used with brainstorming and the solution-and-effect diagram to develop more details of a solution to a problem under consideration.
•Both methods are techniques to expand the horizon of a team searching for answers. These two techniques force a team to develop a better and more detailed understanding of a problem or solution.
How to Use It

•Draw a box at the top of a piece of flip chart paper and clearly write down the problem or solution to be explored.
•Below the statement box draw five lines in descending order.
•Ask the “Why” or “How” question five times and write the answers on the lines drawn from number one to five.
•It may take less or more than five times to reach the root cause or solution.
Examples of five whys and five hows are below.

Five whys of less vigorous exercise:

Too much TV and video games
Why?

Few community-sponsored recreation programs
Why?

No family recreational activities
Why?

No safe play area
Why?

Lack of resources
Why?


Five hows of more vigorous exercise:

Less TV and video games
How?

More community-sponsored recreation programs
How?

More family recreational activities
How?

Safe play areas
How?

Additional resources
How?


Excerpted from Ron Bialek, Grace L. Duffy, and John W. Moran, The Public Health Quality Improvement Handbook (Milwaukee, WI: ASQ Quality Press, 2009), pages 168–170.