When I was young our family had a hand-cranked ice cream maker not unlike the one pictured above, although ours had an aluminum case and not wood. On winter days we would fill the inner cylinder with a mixture of milk, cream, vanilla, sugar, the outer cylinder with ice and salt, sit outside in the snow and churn away. With the right mixture of ingredients and persistence we would have a chilled dessert after a certain amount of time. The making of ice cream in our family wasn't very scientific and results varied from a thick slush to firm sorbet, but rarely very creamy.

The ice cream maker as an analogy for the PDCA problem solving cycle struck me recently while teaching hoshin planning in a locale where the temperature outside was a lovely 41C. Just like the PDCA cycle, the ice cream maker requires constant cranking to make it work. When making ice cream the Plan is the recipe including specifying the ingredients needed based on the desired flavor of ice cream. The Do is to add these to the inner cylinder, ice and salt to the outer cylinder and to commence cranking. The Check is to periodically open up the cylinders to confirm progress, the consistency and flavor. The Act or Adjust is to distribute the slushy center from the liquid freezing to the wall of the cylinder, as well as adding more ice or salt if needed to maintain subzero temperature.

Relevant to the review cycle of hoshin planning, in the PDCA problem solving process it is important to maintain a proper and consistent speed when turning the crank on the ice cream maker. Turn the crank too quickly and you have an uneven distribution of ice cream as the centrifugal force presses some of the liquid against the freezing cold wall of the cylinder. Turn the crank too slowly and the liquid does not move enough, or even at all, and the ice melts before ice cream can form. Either way, the child turning the crank in the snow gets tired without periodic check and adjust. Hoshin planning requires regular face-to-face review to check on progress towards business objectives. Doing this so often that learning is not turned into actions simply wears people out. Turning this cycle too infrequently or stopping altogether is the far more common pitfall of hoshin.

I can't recall exactly why we made ice cream in winter. Perhaps we did so in summer as well but these memories are not as sharp as those of sitting on the front step in snow pants, churning the crank out in the cold. Or perhaps it was because of another hidden life lesson about PDCA, waiting to be discovered 30 years hence: for PDCA to work you must have the right environment. Of course ice cream may be the best treat when the weather is hot, but the old-fashioned ice cream maker would required a lot of ice to work on a 41C day. Likewise with old-fashioned PDCA and hoshin, an organizational environment that allows slow and thorough planning, tolerates mistakes and learning through repeated trial and adjustment is necessary. In hoshin planning it's the leader's job to bring the PDCA ice cream maker to a cool, shaded place, maintain the level of ice and salt, and to bring the rewards out into the heat to share with others.