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Prepares a method comparison two-panel plot. Here is an example
The left panel is a scatterplot mcrnj
prepares a two-panel plot. The left panel is a scatterplot of yvar by xvar. Reference lines at yvar=xvar and yvar = xvar ± caliper are shown. The points in the scatterplot are colored according to whether they are within or outside of the caliper. A predicted line using restricted cubic spline regression of yvar
on xvar
(modeltype(rcs)
is the default option) or Deming regression (modeltype(deming)
) is shown. Two sets of
The right panel is the scatterplot with yvar and derived variables centered at xvar.
Note: the use of the modeltype(deming)
option requires that the deming
module is installed. If you don't have it installed try typing findit deming
.
mcrnj gcp5 gcp6 , modeltype(rcs) ytitle(Video) xtitle(Telephone) note(regression using restricted cubic splines for telephone)
mcrnj gcp5 gcp6 , modeltype(deming) ytitle(Video) xtitle(Telephone) note(regression using Deming regression for telephone)
Using alpha(.1)
will provide 90% confidence intervals. These can be used to approximate two 1-sided t-tests at the 5% significance level that the caliper
. This is an equivalence test of the two measures. (Of course, one could also present 95% CIs and approximate two t-tests at the 2.5% significance level.)
Deming regression is an approach used often in clinical chemsitry to compare two measures. It allows for measurement error in xvar
.