PDCA and the Roads to Rome:

Different roads to take, decision to make

In today’s post, I will be trying to look at the concept of equifinality in relationship to the scientific method PDCA. In Systems Theory, the concept of equifinality is defined as reaching the same end, no matter what the starting point was. This is applicable only in an open system. An open system is a system that interacts with its environment (external). This could be in the form of information, material or energy.

I wanted to look at the repeatability of the PDCA process. PDCA stands for the Plan-Do-Check-Act cycle, and is the framework for the scientific method. If three different people, with different ways of thinking, are facing the same problem, can all three reach the same end goal using the PDCA process? This would imply that equifinality is possible. This concept is shown below. Point A is the initial condition, and point B is the final desired condition. The three different colored lines depicts the three different thinking styles (the different thinking styles indicates the different starting points).


Iterative Nature of PDCA:

The most important point about PDCA is the iterative nature of the cycle. Each cycle of PDCA leads to a new cycle that is more refined. The practitioner learns from each step of the PDCA cycle. The practitioner observes the effect of each step on the problem. Every action is an opportunity to observe the system more. The results of his experiments lead to more experiments, and yield a better understanding of multiple cause-effect chains in the system.

If the scientific method is followed properly, it is highly likely that the three different practitioners can ultimately reach the same destination. The number of iterations would vary from person to person due to different thinking styles. However, the iterative nature of the scientific method ensures that the each step corrects itself based on the feedback. This type of steering mechanism based on feedback loops is the basis of the PDCA process. This idea of multiple ways or methods to have the same final performance result is equifinality. This is akin to the saying “all roads lead to Rome”. This idea of “steering” is a fundamental concept of Cybernetics. I will be writing about this fascinating field in the future.

Final Words:

This post was inspired by the following thought – can a lean purist and a six sigma purist reach the same final answer to a problem if they pursued the iterative nature of the scientific method? There has been a lot of discussion about which method is better. The solution, in my opinion, is in being open and learning from the feedback loops from the problem at hand.

I will finish this post with a neat mathematical card trick that explains the idea of equifinality further. This trick is based on a principle called Kruskal Count.

The Effect:

The spectator is asked to shuffle the deck of cards to his heart’s content. Once the spectator is convinced that the deck is thoroughly shuffled, the magician explains the rules. The Ace is counted as 1, and all the face cards (Jack, Queen and King) are counted as 5. The number cards have the same values as the number on the card.

The spectator is asked to think of any number from 1 to 10. He is then directed to hold the cards face down, and then deal cards face up in a pile. He should deal the amount of cards equal to the number he chose in his mind. The spectator takes a note of the value of the final card dealt. The spectator is directed to deal those many cards face up on the already dealt cards.

deck_discardThis is repeated until the spectator has reached a card at which point there are not enough cards to deal. For example, the card was 8 of Hearts, and there are only six cards remaining. This card is his selected card. He then puts the face up cards on the table on top of the cards he has on his hand. They do all of this while you have your back turned. You easily find their selected card.

The Secret:

All roads lead to Rome. This trick has an over 80% success rate.

The secret is to repeat exactly what the spectator did. You also choose a random number between 1 and 10, and start dealing as described above. Just like the concept of equifinality, no matter which number you chose as your starting position, as you go through the process, you will choose the same set of cards at the end resulting in the same selected card! Try it for yourself. Here is a link to a good paper on this.

Always keep on learning…

In case you missed it, my last post was If the Learner Has Not Learned, Point at the Moon.


One thought on “PDCA and the Roads to Rome:

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s