So, I am doing the Gauss Newton procedure for Non-Linear regression, and this initial code is used to find starting values for the parameters so I can run the non-linear regression on the equation. So the equation is Y = Alpha - EXP[-(Beta + gamma*X)]. You have to find a starting value for alpha from the data by figuring out how to linearize the equation. You can't linearize it, so knowing as X gets large the equation becomes Y = alpha, you pick the largest Y value to throw in for alpha, and then when you take the linearized part of Y with that parameter and run proc reg on it, it should give an intercept and beta value for X that give you starting values for the other parameters. Here is the code for the in-class example: DATA MINING; INPUT W D Y; X = W/D; YB = LOG(1 - Y/35); CARDS; 610 550 33.6 450 500 22.3 450 520 22.0 430 740 18.7 410 800 20.2 500 230 31.0 500 235 30.0 500 240 32.0 450 600 26.6 450 650 15.1 480 230 30.0 475 1400 13.5 485 615 26.8 474 515 25.0 485 700 20.4 600 750 15.0 ; PROC REG; MODEL YB = X; PROC NLIN DATA = MINING METHOD = GAUSS; MODEL Y = A*(1-EXP((-1)*B*X)); PARMS A = 35 B = .8672; OUTPUT OUT=TWO P=PRED R=RESID; PROC PRINT; VAR Y PRED RESID; and the prof ran the original proc reg to get the B parameter before coding the rest
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