A Relative percent difference (RPD) is a measure of precision, calculated by the following formula:
A Rd % = [X1 is X2]/Xave x 100
X1 is the concentration observed with the first detector or equipment;
X2 = concentration observed with the second detector, equipment, or absolute value; and
Xave = average concentration = ((X1 + X2) / 2)
The relative percent difference (RPD) and coefficient of variation (COV) provide a measure of precision, but they are not equal. Below are example duplicate radon results and the corresponding values of relative percent difference and coefficient of variation:
Because of massive spam, the comment function is removed for a while.