hepstats.hypotests.core.discovery module

class hepstats.hypotests.core.discovery.Discovery(calculator, poinull)

Bases: BaseTest

Class for discovery test.

Parameters:

• calculator (BaseCalculator) – calculator to use for computing the pvalues.

• poinull (POI) – parameter of interest for the null hypothesis.

Example with zfit:

>>> import zfit
>>> from zfit.loss import ExtendedUnbinnedNLL
>>> from zfit.minimize import Minuit
>>>
>>> bounds = (0.1, 3.0)
>>> zfit.Space('x', limits=bounds)
>>>
>>> bkg = np.random.exponential(0.5, 300)
>>> peak = np.random.normal(1.2, 0.1, 25)
>>> data = np.concatenate((bkg, peak))
>>> data = data[(data > bounds[0]) & (data < bounds[1])]
>>> N = data.size
>>> data = zfit.data.Data.from_numpy(obs=obs, array=data)
>>>
>>> lambda_ = zfit.Parameter("lambda", -2.0, -4.0, -1.0)
>>> Nsig = zfit.Parameter("Ns", 20., -20., N)
>>> Nbkg = zfit.Parameter("Nbkg", N, 0., N*1.1)
>>> signal = Nsig * zfit.pdf.Gauss(obs=obs, mu=1.2, sigma=0.1)
>>> background = Nbkg * zfit.pdf.Exponential(obs=obs, lambda_=lambda_)
>>> loss = ExtendedUnbinnedNLL(model=signal + background, data=data)
>>>
>>> from hepstats.hypotests.calculators import AsymptoticCalculator
>>> from hepstats.hypotests import Discovery
>>> from hepstats.hypotests.parameters import POI
>>>
>>> calculator = AsymptoticCalculator(loss, Minuit())
>>> poinull = POI(Nsig, 0)
>>> discovery_test = Discovery(calculator, poinull)
>>> discovery_test.result()
p_value for the Null hypothesis = 0.0007571045424956679
Significance (in units of sigma) = 3.1719464825102244

result(printlevel=1)

Return the result of the discovery hypothesis test.

The result can be (0.0, inf), which means that the numerical precision is not high enough or that the number of toys is not large enough. For example if all toys are rejected, the result is (0.0, inf).

Parameters:

printlevel – if > 0 print the result.

Returns:

Tuple of the p-value for the null hypothesis and the significance.

property calculator

Returns the calculator.

property poialt

Returns the POI for the alternative hypothesis.

property poinull

Returns the POI for the null hypothesis.