statsmodels.stats.power.GofChisquarePower.solve_power¶
method

GofChisquarePower.
solve_power
(effect_size=None, nobs=None, alpha=None, power=None, n_bins=2)[source]¶ solve for any one parameter of the power of a one sample chisquaretest
 for the one sample chisquaretest the keywords are:
effect_size, nobs, alpha, power
Exactly one needs to be
None
, all others need numeric values.n_bins needs to be defined, a default=2 is used.
 Parameters
 effect_sizefloat
standardized effect size, according to Cohen’s definition. see
statsmodels.stats.gof.chisquare_effectsize
 nobsint or float
sample size, number of observations.
 alphafloat in interval (0,1)
significance level, e.g. 0.05, is the probability of a type I error, that is wrong rejections if the Null Hypothesis is true.
 powerfloat in interval (0,1)
power of the test, e.g. 0.8, is one minus the probability of a type II error. Power is the probability that the test correctly rejects the Null Hypothesis if the Alternative Hypothesis is true.
 n_binsint
number of bins or cells in the distribution
 Returns
 valuefloat
The value of the parameter that was set to None in the call. The value solves the power equation given the remaining parameters.
Notes
The function uses scipy.optimize for finding the value that satisfies the power equation. It first uses
brentq
with a prior search for bounds. If this fails to find a root,fsolve
is used. Iffsolve
also fails, then, foralpha
,power
andeffect_size
,brentq
with fixed bounds is used. However, there can still be cases where this fails.