A scatter diagram.
The horizontal axis shows histology, a categorical variable with three groups: "Benign", "Prostatitis", and "Cancer". The vertical axis shows "PSA" and is numbered 0, 500, 1000, 1500, and 2000.
For the Benign group the points form a solid mass just above zero. For the Prostatitis group the points also form a solid mass just above zero. For the Cancer group the points are more spread out. There is also a solid mass just above zero, but a few other points stretch above this to PSA = 500 and there is one point at PSA = 1700.
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This page maintained by Martin Bland.
Last updated: 3 August, 2006.