LikelihoodRatioTest

class sherpa.sim.simulate.LikelihoodRatioTest[source] [edit on github]

Bases: sherpa.utils.NoNewAttributesAfterInit

Likelihood Ratio Test.

The likelihood ratio [1], D, is defined as:

          (   likelihood for null model )
D = -2 ln -----------------------------------
          ( likelihood for alternative model)

  = -2 ln(likelihood for null model) +
     2 ln(likelihood for alternative model)

Since the Cash and C fit statistics are defined as -2 ln(likelihood), the equation reduces to:

D = statistic for null model -
    statistic for alternative model

References

[1]http://en.wikipedia.org/wiki/Likelihood-ratio_test

Methods Summary

calculate(nullfit, altfit, proposal, …)
run(fit, null_comp, alt_comp[, conv_mdl, …])

Methods Documentation

static calculate(nullfit, altfit, proposal, null_vals, alt_vals)[source] [edit on github]
static run(fit, null_comp, alt_comp, conv_mdl=None, stat=None, method=None, niter=500, numcores=None)[source] [edit on github]