http://r.789695.n4.nabble.com/file/n3216865/Inverse_Gamma.png
Hello, I am seeking help in estimating the parameters of an inverse gamma distribution (from the 'actuar' package) using a function like 'fitdistr'. Unfortunately I haven't found such a package using findFn('fit Inverse Gamma') from the 'sos' package and was therefore hoping someone might be aware of such a function? Secondly, is there a way to shift the pdf (code below) to the right (rather than the data to the left)? I tried: par(new=T) shift<-1 hist(iniSal_US_forHist,breaks=seq(1.1,21,by=0.625),col="grey",freq=F,xlim=c(0-shift,21-shift),plot=F) curve(dinvgamma(x,scale=11.835,shape=4.4242),from=0,to=20,add=T,col="purple",lwd=2) but this failed in shifting the curve. More broadly, the data plotted in the histogram represents a calibration target for output generated by a finite difference solute transport model. The values that will be generated by the finite difference model would ideally fit the shifted (if that can be figured out) inverse gamma pdf. To the extent that fit is deemed poor, the parameter estimation software associated with the finite difference model will adjust parameters until a better fit is found. I will try to use a goodness of fit test to determine if one set of parameter values in the finite difference model produce output that fits the inv. gamma curve herein better than another. But first I need to establish the curve the finite difference model output should target and would greatly appreciate any leads on how it might be shifted and/or fit more precisely by a fitdistr-like function. library(MASS) library(actuar) iniSal_US_forHist<-c(2.368000,3.532614,3.064330,3.347069,3.066333,4.233636,3.465650,2.858553, 2.946731,2.945417,2.415000,2.873019,5.521000,5.788148,5.314630,5.509672,6.032840,6.009310, 4.110833,6.073182,5.652833,4.425733,6.481852,4.076857,3.289310,4.524000,3.985811,5.399714, 4.490606,6.956729,5.270933,8.099107,5.058250,6.394500,5.644000,5.202459,5.666667,3.152680, 3.220952,2.777381,3.115467,3.642759,3.488333,3.022439,2.610290,2.618571,3.218000,3.417634, 10.327317,7.344270,6.886154,4.015800,3.063103,6.832292,4.600238,2.939000,5.999027,7.894878, 4.411538,2.384762,6.816154,2.782500,2.475333,2.799138,2.739063,2.619917,2.892545,2.468167, 2.577079,2.821875,2.502500,2.969032,2.046023,3.073077,4.408000,3.411774,3.500000,4.283607, 4.284000,4.276714,3.228103,2.639875,3.453194,2.821200,3.838723,1.714253,2.273750,2.611882, 2.321781,2.567500,2.557045,1.288875,2.175211,1.736000,2.250781,7.433366,7.033553,5.474444, 7.132727,8.505937,9.174545,6.554487,7.060286,6.617160,8.210986,4.404045,6.062381,5.149625, 2.972105,5.358889,3.910968,3.715873,1.728966,2.843667,4.413906,3.016346,7.168636,3.839394, 3.930141,7.019882,3.459429,5.050250,3.492714,3.226667,3.987667,2.770227,3.661167,1.553000, 2.867391,2.897193,2.611707,2.577167,2.904697,2.733077,2.507241,11.044865,6.425484,8.567222, 8.552344,7.493396,4.807381,9.697869,9.471333,6.783175,4.563571,8.059649,9.448679,5.803778, 4.769423,4.424634,7.586042,4.451556,3.622373,6.390152,4.424375,4.135806,5.025400,5.410635, 7.012292,2.961071,3.192188,2.989643,3.471429,2.867966,1.980541,3.172344,2.574783,2.958983, 1.708140,3.604853,3.479000,2.845000,2.742603,2.923968,3.620308,2.452500,2.721375,3.166333, 2.742162,2.793000,3.337000,5.192025,5.365875,3.079000,8.415970,6.612277,6.734706,4.856857, 5.164783,7.743667,6.894151,4.666538,9.227167,8.077581,6.109833,6.621724,18.098182,12.705600, 15.490784,17.394750,12.422364,14.832727,8.326000,11.352400,3.431429,2.658261,3.219773,3.605185, 4.030299,3.262241,3.503250,3.522763,2.847312,2.996618,3.075769,3.387731,3.066923,3.078200, 2.466957,3.214167,2.707778,3.384839,2.283556,2.912258,3.378000,2.726750,2.950000,2.195000, 4.819063,3.604578,3.694906,5.068000,4.676582,3.028831,4.261042,3.593235,4.501224,2.880317, 5.750333,3.257833,3.967458,2.522292,2.725738,2.549231,2.591389,2.990488,2.681222,2.685854, 2.284750,2.585938,2.432824,3.108875,2.611340,3.916667,2.418095,2.476406,2.801235,3.278000, 2.434921,2.617826,3.133939,2.774321,4.196173,3.764286,3.555833,5.317361,3.970800,4.136400, 4.487013,3.746393,4.754000,3.854316,3.742353,3.044079,2.817821,3.995179,3.643134,3.642593, 3.604533,2.935902,4.088310,5.344407,3.076883,3.287105,3.720870,2.032258,2.872593,5.787313, 6.017838,5.425205,4.880600,3.582295,4.903333,3.489016,4.603030,5.344407,6.184286,4.047083, 4.788304,4.661325,4.815938,4.056790,3.765595,5.348772,5.200222,4.906311,3.900147,3.782897, 3.767313,3.417732,3.725455,2.888750,2.552333,2.521613,2.531522,2.510833,2.710208,2.445273, 2.619750,2.094737,2.399355,2.758000,2.317077,2.247755,3.594333,4.607805,2.693333,3.084706, 3.529000,2.326200,3.309851,2.647805,2.802250,2.778667,3.231235,2.418065,3.134545,3.807843, 2.988372,2.709792,3.084035,3.633279,2.958750,2.170081,2.674444,2.640706,2.841600,3.399219, 2.561373,2.574824,3.046447,2.647500,3.554875,1.865000,2.858333,2.355000,2.508082,2.376833, 2.728710,1.752833,1.571967,1.800333,2.265455,2.353226,2.568028,2.359500,2.472639,1.675385, 2.667386,2.490000,2.482632,2.593452,2.695510,2.466941,2.624211,3.835645,3.519667,2.661940, 3.516167,3.146585,3.420462,4.809833,3.028500,3.192297,4.256333,2.516897,3.033846,2.793359, 6.700714,5.441250,6.872500,4.528333,7.490328,4.673788,6.376885,3.023167,4.429167,4.317625, 16.729231,8.372500,6.279828,10.805098,8.359452,8.277576,8.008846,8.742308,12.155942,5.975063, 3.317333,2.883021,3.310822,3.119219,3.921190,3.552986,3.647162,4.017667,3.895342,3.381096, 2.769412,3.225294,4.169333,3.733919,2.859492,3.674875,3.401017,3.160267,4.109545,4.347867, 3.867000,3.672763,4.364844,3.804250,2.613000,4.289909,4.212059,4.785797,4.149687,6.299444, 5.640135,5.713448,4.766438,7.032027,5.610533,3.126111,6.322029,4.417692,6.392532,2.753175, 2.549655,3.456533,3.199000,3.852338,3.387549,3.098033,3.271733,3.679180,2.655484,6.858167, 5.808033,7.551111,8.388387,5.108732,7.895152,5.223580,5.741714,8.026250,4.928421,2.797292, 3.052500,2.934615,2.842051,2.869259,2.702400,2.666977,2.935385,2.546471,2.617755,3.020250, 2.922955,3.133500,3.353750,3.101000,2.581235,3.624715,2.376164,3.597467,3.011519,2.885250, 2.642716,2.843788,3.125000,2.394034,3.126125,2.960125,3.553800,3.045733,2.823375,2.953951, 3.170694,3.746500,3.421519,2.876707,3.162206,2.976852,2.912917,3.510784,2.822763,3.245244, 3.322738,3.168776,2.822700,2.898500,4.311667,3.517195,4.239014,3.615676,3.625652,4.693542, 3.426379,3.446250,4.204375,4.061000,2.864167,3.498772,3.817303,2.649300,2.913529,2.773400, 3.844833,3.312581,4.072025,3.578395,3.856429,3.666889,2.554505,2.615469,2.686667,4.848387, 3.182667,3.172364,2.829063,2.998182,2.224000,3.238167,4.072407,5.915490,5.872632,4.942597, 6.163684,5.003750,1.592295,2.398679,2.360000,1.930200,2.341746,2.352031,2.577647,2.286604, 2.172000,2.430889,2.647231,2.748500,2.837692,2.764884,2.511774,3.047451,2.744737,2.733871, 2.666818,3.047800,6.127000,3.212807,7.100615,5.016842,5.404091,4.586324,4.815738,2.667867, 2.583625,3.023099,2.364154,3.033077,2.712821,3.104861,2.451831,10.244054,9.028333,6.488088, 11.350333,10.805227,2.796250,3.901455,8.846500,5.692500,4.502549,9.645833,12.323077,11.690702, 9.757213,10.140000,6.435873,8.559375,12.581639,9.658000,7.910395,10.317167,14.744098,3.019400, 3.196154,2.924583,2.926393,3.435926,2.940968,2.729048,2.419625,3.257031,2.246915,2.405352, 4.807167,3.329661,3.300256,2.626364,2.588714,2.516825,3.369804,2.802381,2.703889,1.899500, 2.624286,3.370244,3.224510,2.587368,3.243881,3.209474,2.644154,3.591132,3.179851,3.118125, 3.428333,3.078033,2.639219,2.392979,3.035208,8.924667,7.126420,4.412626,7.663580,9.798000, 7.091940,6.561806,10.351000,7.816000,5.686581,7.486833,5.878148,5.549032,1.775849,3.393235, 3.730208,3.131846,2.988404,3.922286,3.835077,1.918780,2.614118,2.564207,3.160625,2.085614, 2.498033,1.107183,2.408000,2.226296,3.063281,2.647500,3.149726,1.929091,2.297000,4.035500, 7.813846,18.976765,10.127547,12.294455,5.909020,7.263115,13.789367,6.608750,3.110926,4.948333, 7.655873,5.366154,2.468889,3.215000,3.329375,2.722821,3.115902,2.538235,3.233171,3.060541, 3.377647,2.837049,3.071290,2.293400,3.034937,2.943846,2.987534,2.947222,3.286522,2.794600, 2.950822,1.542667,2.318085,3.049583,2.384250,2.554146,1.761333,2.028356,2.434590,3.128333, 2.838437,3.331000,2.645116,3.038667,2.646000,3.082857,4.406301,4.136000,2.161429,1.832424, 3.027742,3.908958,3.479608,3.566562,2.101875,2.960122,2.804752,2.334105,3.993836,2.878116, 2.828197,2.674353,3.231500,2.468000,2.152400,3.290274,5.412121,2.775909,9.023833,6.593125, 3.417558,4.213469,2.771452,7.874776,2.453871,3.166833,2.657000,2.526111,3.105400,2.973265, 4.900667,3.042551,2.861647,3.745125,3.244643,2.177500,2.119167,2.798000,3.005577,2.837347, 3.211167,3.381358,3.200306,4.640167,5.564706,3.043121,6.172000,2.490000,4.449667,5.433918, 4.652576,3.197619,2.675631,2.547407,3.462195,2.657468,3.016087,2.814262,2.966383,3.288033, 2.278676,2.609537,2.633667,2.815000,3.465000,2.231538,3.161538,3.412667,3.516800,3.249452, 2.418734,3.245455,2.650800,3.634038,3.255484,1.992093,3.184429,3.155200,2.997500,3.887931, 2.597500,3.316406,3.684091,3.707107,4.479692,3.292833,2.806935,2.833143,2.962857,2.229474, 3.786700,4.029756,3.174118,6.493770,4.611944,6.103279,5.899687,2.946711,6.338660,5.237273, 3.413553,3.226667,4.193143,6.192375,9.437436,1.863548,3.185567) #plot it hist(iniSal_US_forHist,breaks=seq(1.1,21,by=0.625),col="grey",freq=F,xlim=c(0,21)) #try fitting it curve(dinvgamma(x,scale=11.835,shape=4.4242),from=0,to=20,add=T,col="blue",lwd=2) -- View this message in context: http://r.789695.n4.nabble.com/Fitting-an-Inverse-Gamma-Distribution-tp3216865p3216865.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list 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.