# 3-parameter Gamma and Weibull distribution

Do exist m-files that I could use to fit 3-parameter
distribution: Gamma and Weibull
.

## Relevant Pages

• Re: Predicting using SAS-Survival analysis
... The problem with simply using the highest likelihood is that those ... one parameter, Weibull, logistic, log-normal, normal, and log-logistic ... are two-parameter distributions, and gamma has three. ... chi-square distribution with 1 degree of freedom, ...
(sci.stat.math)
• Re: Predicting using SAS-Survival analysis
... The problem with simply using the highest likelihood is that those ... one parameter, Weibull, logistic, log-normal, normal, and log-logistic ... are two-parameter distributions, and gamma has three. ... chi-square distribution with 1 degree of freedom, ...
(sci.stat.edu)
• Re: 3-parameter Gamma and Weibull distribution
... Maciej, the most common way to fit univariate distributions is by maximum likelihood, but with a threshold parameter, like the 3-param Gamma and Weibull have, maximum likelihood often doesn't give plausible fits, and sometimes never works at all. ... In the case of the lognormal, the problem is that the ML estimate of the threshold is the smallest observation, and the estimated distribution is degenerate at that point. ...
(comp.soft-sys.matlab)
• Re: Gamma Fit
... I am really confused with the gamma functions matlab ... HISTFIT will both fit and plot, though there are many other ways to make a plot -- you haven't said what kind of plot. ... parameters of a gamma distribution fit to the data in X. PARMHAT ...
(comp.soft-sys.matlab)
• Re: Shape and Scale parameters of Gamma distribution
... It is one way to _estimate_ the distribution parameters of the hypothetical underlying distribution from a sample of data. ... not to fit before generating random number. ... that's what GAMRND does. ... If you mean, "how well does the specific gamma distribution that I have estimated from my data model those data?", then that's the sort of thing that the second output of GAMFIT, or probability plots, or any number of other methods, helps to tell you. ...
(comp.soft-sys.matlab)