I am currently working with non linear regression specifically logistic function. The problem i am facing is that after stating the initial values the outputs remain the same as the default one.
The output remains the same even after specifying b1 as 100.
The output remains the same even after specifying b1 as 100.
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. nl log3 : AllIndia Year, variables(AllIndia) initial(b1 100) (obs = 12) Iteration 0: residual SS = 102.2682 Iteration 1: residual SS = 17.37851 Iteration 2: residual SS = 14.58881 Iteration 3: residual SS = 14.56964 Iteration 4: residual SS = 14.5694 Iteration 5: residual SS = 14.5694 Iteration 6: residual SS = 14.5694 Source SS df MS Number of obs = 12 Model 9559.2474 3 3186.41579 R-squared = 0.9985 Residual 14.569401 9 1.61882235 Adj R-squared = 0.9980 Root MSE = 1.272329 Total 9573.8168 12 797.818064 Res. dev. = 36.38273 3-parameter logistic function, AllIndia = b1/(1 + exp(-b2*(Year - b3))) AllIndia Coef. Std. Err. t P>t [95% Conf. Interval] /b1 47.68555 1.191711 40.01 0.000 44.98971 50.38139 /b2 .7198174 .0500137 14.39 0.000 .6066785 .8329563 /b3 2009.956 .1268771 15841.75 0.000 2009.669 2010.243