Quality Glossary Definition: Scatter diagram Show
Also called: scatter plot, X-Y graph The scatter diagram graphs pairs of numerical data, with one variable on each axis, to look for a relationship between them. If the variables are correlated, the points will fall along a line or curve. The better the correlation, the tighter the points will hug the line. This cause analysis tool is considered one of the seven basic quality tools.
When to Use a Scatter Diagram
Scatter Diagram Procedure
Scatter Diagram ExampleThe ZZ-400 manufacturing team suspects a relationship between product purity (percent purity) and the amount of iron (measured in parts per million or ppm). Purity and iron are plotted against each other as a scatter diagram, as shown in the figure below. There are 24 data points. Median lines are drawn so that 12 points fall on each side for both percent purity and ppm iron. To test for a relationship, they calculate: Then they look up the limit
for N on the trend test table. For N = 24, the limit is 6. Scatter Diagram Example Additional Scatter Diagram ExamplesBelow are some examples of situations in which might you use a scatter diagram:
Scatter Diagram Considerations
Scatter Diagram ResourcesYou can also search articles, case studies, and publications for scatter diagram resources. BooksThe Quality Toolbox ArticlesPitch Perfect (Lean & Six Sigma Review) Learning the ins and outs of capability analysis by examining Pittsburgh Pirates starting pitcher Jameson Taillon’s performance using scatter diagrams. Adapted from The Quality Toolbox, ASQ Quality Press. What is a graphed cluster of dots each of which represents the values of two variables?Scatterplot: A graphed cluster of dots, each which represents the values of two variables. The slope of the dots represents the direction (+ or -) of the relationship while the amount of "scatter" suggests the strength of the correlation.
What predicts how two or more factors are related?A hypothesis is a tentative statement about the relationship between two or more variables. It is a specific, testable prediction about what you expect to happen in a study.
Is a statistical index of the relationship between two things?Correlation is a statistical technique that is used to measure and describe a relationship between two variables.
What is a sample that fairly represents a population because each member has an equal chance of being included?Random Sample Sample that fairly represents a population. Each member has an equal chance of being chosen. One participant from the survey mentioned above selected at random.
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