DA.reg {MethComp}R Documentation

Make a regresion of differeneces on averages

Description

For each pair of methods in data, a regression of the differences on the averages between methods is made and a linear relationship between methods with prediction standard deviations is derived.

Usage

  DA.reg(data)
  

Arguments

data A Meth object. May also be a data frame with columns meth, item and y.

Details

If the input object contains replicate measurements these are taken as separate items in the order they appear in the dataset.

Value

A three-dimensional array, with dimensions From, To (both with levels equal to the methods in data) and an unnamed dimension with levels "alpha", "beta", "sd.pred", "beta=1" and "s.d.=K". Conversting from method j to method k using

y_{k|l}=α+β y_l

with prediction standard deviation σ, just requires the entries [l,k,c("alpha","beta","sd.pred"]. The two last entries ae p-values for the hypothese the β=1 and that the standard error is constant over the range.

Author(s)

Bendix Carstensen, Steno Daibetes Center, bxc$steno.dk

References

B Carstensen: Limits of agreement: How to use the regression of differences on averages. Technical Report 08.6, Department of Biostatistics, University of Copenhagen, http://www.pubhealth.ku.dk/bs/publikationer/Research_report_08-6.pdf, 2008.

Examples

data( milk )
DA.reg( milk )
round( ftable( DA.reg( milk ) ), 3 )
data( sbp )
round( ftable( DA.reg( sbp ) ), 3 )

[Package MethComp version 0.5.0 Index]