When brainstorming root cause with a cause and effect diagram, for instance, the team may come up with a large number of possible causes. You may not have the time and resources to investigate all of them, so you need to prioritize. You can also use this tool for other team decisions, like selecting a process improvement or a vendor. This tool might be used in the analyze phase when determining root cause, or it might be used in the improve phase when selecting an improvement. It's easy to do a prioritization matrix in Excel. There is a little math involved, so Excel simplifies this as well. In this first example, we'll use the tool to select a vendor from three possibilities. Across the top row, the team will list their decision criteria. These are not predetermined. This is one of several team decisions that must be agreed upon as you use the tool. After discussion, the team decided that the most important criteria for this selection were cost, quality, flexibility and delivery. But cost, quality, flexibility and delivery are not of equal importance. So the team must decide how to weight these factors. We use decimals, but you can also use percentages. The team decided that quality was the most important factor and gave it a weight of 0.4 or 40 percent. Cost was 0.3 or 30 percent. Delivery was the next most important criteria at 0.2 or 20 percent and flexibility was weighted at 0.1 or 10 percent. Regardless of how many criteria you choose, the weights must add up to one or 100 percent. The next step is to rank order the options, with the largest number being the most desirable. The team determined that Vendor C had the best price, followed by Vendor A and Vendor B was the most expensive. So since B was most expensive, it gets the lowest ranking - one. Vendor C was the most desirable price, so it is three. This is repeated for each criterion. Each time you assign a ranking to the options based on a criterion, the team will have a conversation and reach consensus. This tool takes some time. Once all the options have been ranked against all the criteria, you'll multiply each ranking by the weight assigned for that criterion. For example, under cost, Vendor A was ranked number two so we multiply two times the relative importance of cost, which is 0.3. The result is 0.60. Vendor B was the most expensive, so it has a ranking of one and its score is 0.30. Finally, Vendor C had the most desirable price, so its score will be the weight, or relative importance, times its ranking of three; so its score is 0.90 on the cost criteria. Repeat this for every option and each criterion. The multiplication and addition can be done more quickly and reliably if you use Excel. Once you've created a score for each option against each criteria, you can add the scores for each option going across. The scores here are shown in parentheses. So for Vendor A, it's 0.6 plus 0.4 plus 0.3 plus 0.6 for a total of 1.90. Repeat this for each option, adding across. The highest total score is probably the most desirable choice. A caution about the prioritization matrix. As we go through this process, we're assigning weights and ranks and multiplying and adding numbers, so this feels like it's quantitative, but it is not. The team decides what those weights and ranks will be, so it's qualitative. The real value is in all of the team discussions. The team has to discuss and decide what the criteria will be. The team will have another discussion to decide what the weights will be. Then the team will have yet another discussion to decide on how to rank the options. The real value in this tool is in these discussions. Through this process, the team gets a deeper understanding of the decision it's making. Do not let the numbers make the decision. Sometimes a team, after all this discussion, will decide on the option with the second highest score; because after all of the discussion, they may decide that the weighting or their ranking were not quite right. Let's look at another example. This time we're selecting which improvement option to give priority to. In this case, the team has chosen the following criteria and weights. The cost of the implementation is first, with a weight of 30 percent or 0.3. Speed of implementation is the most important because, we want to be able to demonstrate some quick results to gain buy-in; so it's weighted at 40 percent. Complexity is probably closely related to speed, but the team decided to include it and its weight is 10 percent. And finally, the benefits of the improvement are weighted at 20 percent. When we rank the options, the team felt that improvement two and improvement three were the same on the speed criteria. If there is a tie like this, use the value halfway between. So the team could not decide which was one and which was two, so they ranked them both 1.5. Now we multiply the relative importance or weight times the ranking just as we did before and add up the scores for each improvement option. Improvement number one had the highest score. Since the score between improvement one and improvement two is fairly close, the team might have some additional discussion about this. However, since improvement one had the highest score in the most important criteria and was no lower than second in any other, it seems likely that the team would choose improvement number one. Remember, the team makes the decision, not the tool.
