This is a scatter diagram.
The horizontal axis shows Baseline standard deviation of peak expiratory flow in litres per minute and is numbered 0, 20, 40, 60, 80, 100. The vertical axis shows log standard deviation of peak expiratory flow after six months and is numbered 1, 2, 3, 4, 5.
There are two overlapping clouds of points labeled Intervention and Control. Both clouds are distributed about parallel rising straight lines about 0.4 apart. The Intervention cloud and line are lower than the Control cloud and line. For each group the observations are scattered up to one unit on either side of the line.
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This page maintained by Martin Bland.
Last updated 11 August 2008.