Six Sigma Green Belt Certification Practice Exam

In the C sub P index formula, what does the standard deviation represent?

1. The tolerance interval

2. The confidence interval for the result

3. The range of the process

4. The variance of the index

The correct answer is: The tolerance interval

In the C sub P index formula, the standard deviation is a crucial component that represents the spread of the process data. It reflects how much variation exists in the process measurements. Specifically, the standard deviation is used to assess how consistently the process performs within the given specifications. The correct choice identifies the relationship between the standard deviation and the tolerance interval. The tolerance interval encompasses the upper and lower specification limits that define the acceptable range of variation in the process. By incorporating the standard deviation into the C sub P formula, you can evaluate how well the process can meet the defined tolerance levels. A smaller standard deviation relative to the range of the tolerance indicates a more capable process. Other answers do not accurately describe the role of standard deviation in this context. For example, while the confidence interval relates to the estimation of a population parameter based on sample data, it does not directly pertain to the standard deviation within the context of the C sub P index. The range of the process and variance represent different statistical concepts that do not capture the function of standard deviation in relation to tolerance intervals.