Good morning gentlemen! How using a weighted model in nls2? Values with the nls are logical since values with nls2 are not. I believe that this discrepancy is due to I did not include the weights argument in nls2.
Here's an example: MOISTURE <- c(28.41640, 28.47340, 29.05821, 28.52201, 30.92055, 31.07901, 31.35840, 31.69617, 32.07168, 31.87296, 31.35525, 32.66118, 33.23385, 32.72256, 32.57929, 32.12674, 52.35225, 52.77275, 64.90770, 64.90770, 85.23800, 84.43300, 68.96560, 68.41395, 70.82880, 71.18400, 96.13240, 96.07920, 95.35160, 94.71660, 87.59190, 88.63250, 89.78760, 90.17820, 88.46160, 87.10860, 94.86660, 94.51830, 75.79000, 76.98780, 144.70950, 143.88950, 111.58620, 112.71510, 120.85300, 121.43100, 116.34840, 114.87420, 195.35040, 191.36040, 265.35220, 267.25450, 227.13700, 228.78000, 238.37120, 242.70700, 299.54890, 291.04110, 220.09920, 219.82650, 236.79150, 243.70710, 208.79880, 208.12260, 417.21420, 429.59480, 360.91080, 371.66400, 357.72520, 360.53640, 383.82600, 383.82600, 434.02700, 432.57500, 440.56260, 438.32340, 468.69600, 469.82140, 497.93680, 497.17010) YEARS <- rep(c(86,109, 132, 158, 184, 220, 254, 276, 310, 337),c(8,8,8,8,8,8,8,8,8,8)) VARIANCE <- c(2.0879048 , 2.0879048, 2.0879048, 2.0879048, 2.0879048, 2.0879048, 2.0879048, 2.0879048, 0.3442724, 0.3442724, 0.3442724, 0.3442724, 0.3442724, 0.3442724, 0.3442724, 0.3442724, 151.9481710, 151.9481710, 151.9481710, 151.9481710, 151.9481710, 151.9481710, 151.9481710, 151.9481710, 115.3208995, 115.3208995, 115.3208995, 115.3208995, 115.3208995, 115.3208995, 115.3208995, 115.3208995, 51.9965027, 51.9965027, 51.9965027, 51.9965027, 51.9965027, 51.9965027, 51.9965027, 51.9965027, 180.0496045, 180.0496045, 180.0496045, 180.0496045, 180.0496045, 180.0496045, 180.0496045, 180.0496045, 791.3223240, 791.3223240, 791.3223240, 791.3223240, 791.3223240, 791.3223240, 791.3223240, 791.3223240, 1280.0179973, 1280.0179973, 1280.0179973, 1280.0179973, 1280.0179973, 1280.0179973, 1280.0179973, 1280.0179973, 728.9582154, 728.9582154, 728.9582154, 728.9582154, 728.9582154, 728.9582154, 728.9582154, 728.9582154, 752.4591144, 752.4591144, 752.4591144, 752.4591144, 752.4591144, 752.4591144, 752.4591144, 752.4591144) test <- data.frame(YEARS,MOISTURE,VARIANCE) mod.nls <- nls(MOISTURE ~ A/(1+B*exp(-k*YEARS)), data = test, weights = 1/VARIANCE, start = list(A=1500, B=200, k=0.03345), control=list(maxiter = 500), trace=TRUE) summary(mod.nls) Following the example of pdf! st1 <- expand.grid(A = seq(0, 2000, len = 10), B = seq(0, 500, len = 10), k = seq(-1, 10, len = 10)) st1 mod.nls2 <-nls2(MOISTURE ~ A/(1+B*exp(-k*YEARS)), data = test, start = st1, algorithm="brute-force") mod.nls2 I appreciate everyone's attention. -- View this message in context: http://r.789695.n4.nabble.com/How-using-the-weights-argument-in-nls2-tp2524328p2524328.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.