I've been banging my head against the wall a bit with this and would be ecstatic if someone could help.
Initial data: Response Dose 1 285.17 0.125 2 377.65 0.250 3 438.99 0.500 4 338.46 1.000 5 227.87 2.000 6 165.96 0.010 7 302.92 0.125 8 418.50 0.250 9 464.69 0.500 10 301.36 1.000 11 213.12 2.000 12 160.34 0.010 13 306.18 0.125 14 435.37 0.250 15 451.34 0.500 16 319.50 1.000 17 219.83 2.000 18 172.52 0.010 19 306.56 0.125 20 439.01 0.250 21 469.74 0.500 22 318.05 1.000 23 223.09 2.000 The graphpad template that that this normally would be placed in then transforms the taking the log(Dose,base=10) and normalizes the Response. I've confirmed that I was able to recreate that here: NormResponse LogDose 1 41.011 -0.90309 2 72.909 -0.60206 3 94.067 -0.30103 4 59.392 0.00000 5 21.246 0.30103 6 -0.108 -2.00000 7 47.133 -0.90309 8 87.000 -0.60206 9 102.932 -0.30103 10 46.595 0.00000 11 16.159 0.30103 12 -2.047 -2.00000 13 48.258 -0.90309 14 92.819 -0.60206 15 98.327 -0.30103 16 52.852 0.00000 17 18.473 0.30103 18 2.155 -2.00000 19 48.389 -0.90309 20 94.074 -0.60206 21 104.674 -0.30103 22 52.352 0.00000 23 19.598 0.30103 Now graphpad used 'log(inhibitor) vs. normalized response -- Variable slope' which it states to be a 4parameter sigmodial but it gives me very different results. graphpad gives and IC50 of 0.1560 and drm's LL.4 gives 0.1149 and it wont even take the transformed data,just throws an error. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.