8.7 Tools: YX Matrix

During the Measure phase, you and your team prioritize data collection, as not all available data provide value to your project. A helpful tool in that task is the YX matrix. According to the American Society for Quality (ASQ), the YX matrix is a tool that allows a team or individual to make informed decisions by comparing two sets of information and analyzing the relationships between them. The tool’s goal is to help you prioritize. It mathematically computes the correlation between key process input variables (Xs) and customer outputs (Ys).

Again, the YX matrix allows you to prioritize the input process parameters (Xs). It illustrates the correlation of process inputs to customer's outputs. You build the matrix using a group of columns and rows, with factor X (input) represented by the horizontal axis and factor Y (output) represented by the vertical axis. Figure 8.6 displays the primary form of the YX matrix. Let’s take a look at how to populate the matrix and produce the results for analysis.

Imagine that your organization wants to improve its logistics operations to reduce waste in the form of inventory. Your senior manager asked for your help in prioritizing the potential variables that can impact four crucial output variables. To set up the YX matrix, you can put the team together and develop likely Xs through brainstorming and using information from the process map. The senior leadership team has provided you with the output variables in this case. The list below summarizes the steps necessary for you to build the matrix:

1. Prepare a list of potential input variables (Xs).

2. Enter a list of essential output variables (Ys or CTQs) into the matrix.

3. Rate each Y from 1 (least significant) to 10 (most important).

4. Enter all potential input variables (Xs) that impact each Y.

5. Rate each X’s impact on each Y from 1 (least) to 10 (most significant).

6. Calculate the weighted sum against each X and record them in the matrix.

7. Analyze the results.

An important point you need to observe here is that populating the matrix is based on quantifying what the team thinks is most important. This procedure means that you are not leveraging hard data, so you need to see the results with skepticism and discuss the outcome’s logic and reasonableness. That said, looking at Figure 8.3, you have a priority direction indicating where to start looking for the factors causing the problem.

In this case, carrier reliability and network design seem to be an excellent place to start. You can now use the YX matrix summary to focus on the high-priority Xs to begin measuring and testing these inputs’ effects on the outputs. A bonus is that you and your team will engage in deep discussions about potential causes for the issues in using the tool.