The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

Matrix Data Analysis Chart (MDAC): How to do it

The Quality Toolbook > Matrix Data Analysis Chart (MDAC) > How to do it

When to use it | How to understand it | Example | How to do it | Practical variations

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How to do it

1. Identify the items which are to be compared, and decide on the primary objective of using the Matrix Data Analysis Chart. For example, a restaurant may compare menu items with the objective of finding out what makes popular dishes.
    
2. Identify the measurement units for the horizontal and vertical axes of the chart. These should be two factors which are the most critical representations of the objective identified in step 1. For example, the restaurant may use a survey to find the aspects of eating that their customer most value.
    
3. Measure the factors identified in step 2, aiming to get realistic and unbiased values. Thus, the restaurant might take an average of customer ratings for texture and flavor of each menu item over several months.
    
4. Draw a chart and plot each point on it. Ensure that the scale on the axes results in the points being spread over the whole chart area.
    
5. Look for significant clusters of points on the chart, and highlight them by linking them together into a ring. The appearance and ease of interpretation are more important than the order of linkage. Groups may be either of:

• Items that have a close logical relationship, e.g. fish dishes.
• Items that form a close physical group on the chart.
   

6. Interpret the chart and act on the results. Typical activities include the investigation into and subsequent action on:

• Why items which might be expected to group closely do not.
• Why items unexpectedly form clusters.
• Why individual items are not positioned where they were expected to be on the chart.

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