This is a scatter diagram, showing the first F E V measurement for the subject on the horizontal axis and the second F E V measurement on the vertical axis. There is a strong positive relationship. There is an oval cloud of points with no increase in variability as F E V increases. There are a few outliers.

The graph is split vertically at first F E V = 1.5 litres. Points to the left of this vertical split are shown as red diamonds, points to the right of this vertical split are shown as blue squares.

Back to Measurement in Health and Disease: Measurement error.

This page maintained by Martin Bland.

Last updated: 21 April, 2008.