Six Sigma Green Belt Certification Practice Exam

Which Six Sigma tool is essential for assessing the relationship between process inputs and outputs?

1. Scatter plot

2. Histogram

3. Control chart

4. Box plot

The correct answer is: Scatter plot

The scatter plot is an essential tool in Six Sigma for assessing the relationship between process inputs and outputs because it visually represents the correlation between two quantitative variables. By plotting these variables on a two-dimensional graph, you can easily identify patterns, trends, and potential causal relationships. This is particularly valuable during the Analyze phase of the DMAIC process, where understanding the impact of inputs on outputs is crucial for process improvement. Using a scatter plot, practitioners can discern whether a strong relationship exists, whether it's positive or negative, or if the relationship is weak or nonexistent. This insight helps in making data-driven decisions and identifying areas for further analysis or experimentation. While histograms, control charts, and box plots each have their roles in data analysis, they do not specifically assess the relationship between two variables in the way that scatter plots do. Histograms display the distribution of a single variable, control charts monitor process variability over time, and box plots summarize the central tendency and variability of a dataset. Each of these tools serves important functions, but for assessing input-output relationships, the scatter plot is the most appropriate choice.