statsmodels.sandbox.distributions.extras.SkewNorm2_gen.fit

SkewNorm2_gen.fit(data, *args, **kwds)

Return MLEs for shape, location, and scale parameters from data.

MLE stands for Maximum Likelihood Estimate. Starting estimates for the fit are given by input arguments; for any arguments not provided with starting estimates, self._fitstart(data) is called to generate such.

One can hold some parameters fixed to specific values by passing in keyword arguments f0, f1, ..., fn (for shape parameters) and floc and fscale (for location and scale parameters, respectively).

Parameters:

data : array_like

Data to use in calculating the MLEs.

args : floats, optional

Starting value(s) for any shape-characterizing arguments (those not provided will be determined by a call to _fitstart(data)). No default value.

kwds : floats, optional

Starting values for the location and scale parameters; no default. Special keyword arguments are recognized as holding certain parameters fixed:

f0...fn : hold respective shape parameters fixed.

floc : hold location parameter fixed to specified value.

fscale : hold scale parameter fixed to specified value.

optimizer : The optimizer to use. The optimizer must take func,

and starting position as the first two arguments, plus args (for extra arguments to pass to the function to be optimized) and disp=0 to suppress output as keyword arguments.

Returns:

shape, loc, scale : tuple of floats

MLEs for any shape statistics, followed by those for location and scale.

Notes

This fit is computed by maximizing a log-likelihood function, with penalty applied for samples outside of range of the distribution. The returned answer is not guaranteed to be the globally optimal MLE, it may only be locally optimal, or the optimization may fail altogether.