Two graphs, a scatter diagram and a Normal plot.
The scatter diagram has the "Mean root CRP" on the horizontal axis numbered 2, 4, 6, 8, and 10. The vertical axis is labeled "Difference in square root CRP, last minus first" and numbered -10, -50, 0, 5, and 10. There is a horizontal line through difference = zero.
The points form a rough triangle with apex at mean = 1.5, difference = zero and sides going from the apex to mean = 10, difference = +10, and to mean = 10, difference = -10, with some points inside the triangle and one outside at mean = 3.5, difference = -7.
The Normal plot has CRP difference on the vertical axis and Inverse Normal on the horizontal axis. The line of points starts below the straight line of perfect Normal distribution then rises above it, then falls below it, then rises above it again. The line of points is closer to the straight line than it was for the untransformed CRP data.
Back to Clinical Biostatistics: Transformations.
This page maintained by Martin Bland.
Last updated: 8 August, 2006.