Hello R-help Does anyone know if there is a package for global fit analysis and if so how to use it. I am trying to calculate the Kd value of a protein interacting with its ligand (When protein interacts with ligand this effect a number of residues). The table below shows with increasing concentration of ligand changes in three different residues. Concentration res1 res2 res3 0 0 0 0 1.99167E-05 0.012978 0.020862 0.03032 3.95847E-05 0.019562 0.032288 0.048266 7.82652E-05 0.021842 0.036 0.05521 0.000115656 0.025274 0.043862 0.06398 0.000151801 0.029896 0.048762 0.075302 0.000186741 0.033544 0.053556 0.084334 0.000220516 0.035676 0.058964 0.0914 0.000274932 0.037834 0.061818 0.097096 0.000352021 0.040694 0.066216 0.100024 0.000422686 0.04329 0.070414 0.109974 0.000552238 0.045482 0.074646 0.116072 0.000777155 0.047062 0.07671 0.118722 0.0012 0.05345 0.08602 0.130344 thanks Asan [[alternative HTML version deleted]]