In the Improve phase of a Six Sigma project, we typically need to choose between two or more potential solutions to a problem. There are several tools to help in making this decision, one of which is pairwise ranking. Pairwise ranking is used by individuals or teams to qualitatively prioritize a list of alternatives. There are many variations of this technique, but all force you to rank all items against each other. We will illustrate the six-step approach with an example.
Step One – List the alternative solutions and identify each with a letter. For our example, we will compare five alternative dinner entrée choices. The alternatives are A – Filet Mignon, B – Lobster Tail, C – Veal Marsala, D – Rack of Lamb and E – Atlantic Salmon.
Step Two – Draw a matrix with as many columns and as many rows as there are alternatives. Black out the cells that represent comparing an item to itself, and the cells that would cause a duplicate comparison.
Step Three – Develop comparison criteria that will be used to compare one alternative to another. For our example, the criteria will be taste, price, and personal preference.
Step Four – Compare each item to every other item, one cell at a time, until you have filed in the matrix. Record the results by entering the preferred alternative in the cell where each pair of alternatives intersect. Here are the results for one individual:
Step Five – Tally the number of times each alternative was chosen. The results are A Filet Mignon = 4, B Lobster Tail = 3, C Veal Marsala = 2, D Rack of Lamb = 0 and E Atlantic Salmon = 1. The preferred entree is Filet Mignon, with Lobster Tail a close second.
Step Six – Look for ways to improve the preferred alternative by incorporating elements of other alternatives. A menu offering of surf and turf (Filet Mignon and Lobster Tail) would be a good hybrid alternative.
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About the author: Mr. Roger C. Ellis is an industrial engineer by training and profession. He is a Six Sigma Master Black Belt with over 50 years of business experience in a wide range of fields. Mr. Ellis develops and instructs Six Sigma professional certification courses for Key Performance LLC. For a more detailed biography, please refer to www.keyperformance.com.