Dear R-helpers, I am trying to plot a Bland-Altman-Plot using the BA.plot function from the package MethComp. While there is a function to transform the values for analysis as shown in the snippet below, I would like to have logarithmic axes for display as well. The usual log = 'xy' does not work because of the properties of the y-asxis (positive and negative values). I am sure that there is a way but I haven't found it. Any suggestions? Best regards an many thanks in advance Thorsten ---- begin code snippet ---- example <- data.frame(meth = c('Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2', 'Marker 1', 'Marker 2'), item = c('QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP1', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2', 'QC12_2_TP2'), repl = c('BER', 'BER', 'BRI', 'BRI', 'BRU', 'BRU', 'COP', 'COP', 'FRA', 'FRA', 'BER', 'BER', 'BRI', 'BRI', 'BRU', 'BRU', 'COP', 'COP', 'FRA', 'FRA'), y = c(7e-04, 9e-04, 4e-04, 4e-04, 8e-04, 7e-04, 5e-04, 7e-04, 5e-04, 6e-04, 0.0049, 0.0048, 0.0054, 0.0052, 0.00508, 0.00462, 0.0049, 0.0043, 0.0048, 0.0045)) example <- Meth(example) BA.plot(example, col.points = rainbow(12), main = 'Bland-Altman analysis', Transform = 'log') rm(example) ---- end code snippet ---- -- Thorsten Raff 2nd Medical Department, University Hospital Schleswig-Holstein, Campus Kiel Chemnitzstra?e 33 24116 Kiel GERMANY phone: +49 431 1697-5234 fax: +49 431 1697-1264 email: t.raff<at>med2.uni-kiel.de web: www.uk-sh.de