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help for ^wbull^
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Fitting Weibull distribution by maximum likelihood
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    ^wbull^ varname [^if^ exp] [^in^ range] [weight] [, ^l^og ]

Description
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^wbull^ fits a Weibull distribution to a single variable by the method
of maximum likelihood. Frequency weights may be used to fit variables
given in frequency distribution form.

The distribution is here parameterised by a scale parameter b and a
shape parameter c, so that the probability density function is

                           c - 1               c
    f(x) = (c / b)  (x / b)       exp(- (x / b) )

for x >= 0, b > 0 and c > 0.

The estimation is carried out by ^weibull^.  Its _b[_cons] is ln b, and
its [ln_p][_cons] is ln c.

Option
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^log^ specifies that the results of ^weibull^ should be displayed.

Example
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        . ^wbull x^

Saved values
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    S_1      number of values used
    S_2      ML estimate of b
    S_3      ML estimate of c

References
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Evans, M., Hastings, N. and Peacock, B. 1993. Statistical distributions.
New York: John Wiley.

Johnson, N.L., Kotz, S. and Balakrishnan, N. 1994. Continuous univariate
distributions: Volume 1. New York: John Wiley.

Author
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         Nicholas J. Cox, University of Durham, U.K.
         n.j.cox@@durham.ac.uk

Also see
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 Manual:  [R] weibull
On-line:  help for @weibull@
