Go back to Flu Mortality


Result for the “BFGS” method for the 1989-1900 epidemic:

For the guess of parameters beta1 = 0.3 alpha1 = 0.2 Ne = 1377 I1 = 1 beta2 = 0.3 alpha2 = 0.2 I2 = 1, we obtained

beta1 = 5.280657e+00 alpha1 = 4.651532e+00 Ne = 1.376953e+03 I1 = 6.976663e-03 beta2 = 2.261040e+00 alpha2 = 1.417738e+00 I2 = 1.179858e+00

So, this implies that f = 1376.953/27653146 = 0.000049793

The covariance matrix was

           [,1]         [,2]          [,3]          [,4]

[1,] 0.474722028 0.465547432 4.287726e+01 -1.941503e-03 [2,] 0.465547432 0.457593268 4.337841e+01 -1.828452e-03 [3,] 42.877259755 43.378409548 1.215924e+04 -2.168046e-02 [4,] -0.001941503 -0.001828452 -2.168046e-02 1.491067e-05 [5,] 0.013010215 0.013807399 1.859597e+01 2.046499e-04 [6,] 0.026089296 0.027021407 1.998082e+01 1.710319e-04 [7,] 0.065642987 0.065929939 -1.574266e+00 -2.860954e-04

            [,5]          [,6]          [,7]

[1,] 0.0130102146 0.0260892959 0.0656429868 [2,] 0.0138073989 0.0270214069 0.0659299386 [3,] 18.5959718481 19.9808204217 -1.5742656729 [4,] 0.0002046499 0.0001710319 -0.0002860954 [5,] 0.0631796289 0.0596675018 -0.0558128983 [6,] 0.0596675018 0.0577938310 -0.0446388989 [7,] -0.0558128983 -0.0446388989 0.1025670873

The MLE was 4045.962

Here’s a plot of the model with the data (red is the data, blue is the sum of the two models, green is the lamb2 model, and purple is the lamb1 model)

two_sir_models_for_our_data_bfgs_.pdf