[R] weighted 2 or 3 parameter weibull estimation?

[Jeff D. Hamann]

  I've figured out how to use optim (barely) to estimate 2 parameter =
  weibull distributions. I can't get over how easy this is. What I need to =
  do is use a weight in the observations.....

  For example,=20

  the tree diameters and weights are are=20

  4.70 , 100
  6.00, 98
  7.10,  75.0
  8.10, 86.3
  8.60, 80.456
  8.90, 20.5
  9.50, 16.6
  11.40, 12.657
  11.80, 12.47
  14.50, 8.98
  16.00,4.5
  16.90,2.36
  18.90, 0.256

  which yield

 LOCATION =3D   0.0000              MEAN =3D   10.9921
    SCALE =3D  12.3436          VARIANCE =3D   18.0027
    SHAPE =3D   2.8050          SKEWNESS =3D    0.2354

  which are the values without the weights. I can't find any reference to =
  weights in the optim function and I'm afraid I'm a little stuck here. =
  After I figure out how to include the weights, I'll then need to =
  estimate the 3-parameter estimates. Any help would be greatful.=20

  Thanks,
  Jeff.


Jeff D. Hamann
Hamann, Donald & Associates, Inc.
PO Box 1421
Corvallis, Oregon USA 97339-1421
Bus. 541-753-7333
Cell. 541-740-5988
jeff_hamann at hamanndonald.com
www.hamanndonald.com




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