Six Sigma Green Belt Certification Practice Exam

A process is examined and four types of errors are observed. Which measurement scale was used in this scenario?

1. Ratio

2. Ordinal

3. Interval

4. Nominal

The correct answer is: Ordinal

In this scenario, the observation of four types of errors indicates that the errors can be categorized but not necessarily ordered in a meaningful way that reflects a rank. A nominal scale is used to classify data into distinct categories without any implication of order, which is typically appropriate for variables that represent different groups or types (like different types of errors). An ordinal scale, on the other hand, does allow for ranking but not precise differences between the values. The context of the question suggests that the focus is on classification of distinct types of errors. Therefore, while an ordinal scale would indicate some sort of ranking, the emphasis on simply recognizing different types of errors aligns more closely with the nominal scale, where the order is irrelevant. To clarify, nominal measurements categorize data without any rank or order, making them suitable for identifying types of items or events. This indicates that the correct measurement scale in this scenario would actually be nominal rather than ordinal, as we are looking primarily at types or categories rather than ranking them.