Scatter Diagram

Posted on February 10, 2009 by

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The Scatter Diagram (also called Scatter Plot) graphically illustrates data from two variables. It is listed as a tool and technique of the fourth edition PMBOK®’s Perform Quality Control process. One of the two variables is on the x-axis, and the other variable is portrayed on the y-axis. In this fictional example, 17 people were given IQ tests and were then asked how many books they owned. Their IQ scores are shown on the y-axis, and the number of books they own are on the x-axis, so the red dot illustrates an individual with an IQ of 130 who owns 200 books. The dots are showing a general pattern of the higher the IQ, the more books that are owned. This is called a positive correlation, because the variables are increasing together. If we had seen the opposite pattern—that the higher the IQ, the fewer books that are owned, it would be a negative correlation because one variable increases as the other decreases.

Scatterplot

Scatterplot