This is a scatter diagram showing the difference between PEFR by the two meters, large minus mini, on the vertical axis and the average of the PEFR measurements by the two meters on the horizontal axis. There is no obvious relationship between the variables. Three horizontal straight lines are shown, marked mean + 2SD, mean, and mean - 2SD. The points are all between the outer lines, except one just below, and touching, the lower line.
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Last updated: 13 January, 2004.