-deming-'s input parameters -cv1()- and -cv2()- correspond to the
coefficients
of variations of the first and second methods (variables var1 and var2,
respectively). These parameters reflect the precision of measurements
for
each of the two methods relative to the mean values. The coefficients
of
variations are used to compute the error variance ratio "lambda" as
follows:
lambda = cv2*mean(var2)/cv1*mean(var1). Note that in -deming-'s output
the
estimate of "lambda" is labeled as the "Variance ratio".
Alternatively, the precision of measurements may be obtained from the
duplicate measurements (if available) by computing the standard error of
the
difference between the duplicates for each method. The variance ratio
is then
computed as a ratio of these standard errors. This alternative
specification,
however, is not available with -deming-.
In the absence of repeated measurements, Subramanian should obtain the
values
of the coefficients of variations for the two methods based on previous
experience and the nature of the considered methods. By default,
-deming-
assumes coefficients of variations of 20% for each method.
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