[R] weighted 2 or 3 parameter weibull estimation?

[Timothy H. Keitt]

Without knowing your cost function (i.e., that passed to optim) its hard
to help.

T.

On Fri, 2002-04-05 at 02:19, Jeff D. Hamann wrote:
> 
>   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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