statsmodels.stats.power.GofChisquarePower.solve_power¶
- 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 chisquare-test
- for the one sample chisquare-test 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_size
float
standardized effect size, according to Cohen’s definition. see
statsmodels.stats.gof.chisquare_effectsize
- nobs
int
orfloat
sample size, number of observations.
- alpha
float
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.
- power
float
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_bins
int
number of bins or cells in the distribution
- effect_size
- Returns
- value
float
The value of the parameter that was set to None in the call. The value solves the power equation given the remaining parameters.
- value
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.