statsmodels.stats.power.FTestPower.plot_power

FTestPower.plot_power(dep_var='nobs', nobs=None, effect_size=None, alpha=0.05, ax=None, title=None, plt_kwds=None, **kwds)

Plot power with number of observations or effect size on x-axis

Parameters:

  • dep_var ({'nobs', 'effect_size', 'alpha'}) – This specifies which variable is used for the horizontal axis. If dep_var=’nobs’ (default), then one curve is created for each value of effect_size. If dep_var=’effect_size’ or alpha, then one curve is created for each value of nobs.

  • nobs ({scalar, array_like}) – specifies the values of the number of observations in the plot

  • effect_size ({scalar, array_like}) – specifies the values of the effect_size in the plot

  • alpha ({float, array_like}) – The significance level (type I error) used in the power calculation. Can only be more than a scalar, if dep_var='alpha'

  • ax (None or axis instance) – If ax is None, than a matplotlib figure is created. If ax is a matplotlib axis instance, then it is reused, and the plot elements are created with it.

  • title (str) – title for the axis. Use an empty string, '', to avoid a title.

  • plt_kwds ({None, dict}) – not used yet

  • kwds (dict) – These remaining keyword arguments are used as arguments to the power function. Many power function support alternative as a keyword argument, two-sample test support ratio.

Returns:

If ax is None, the created figure. Otherwise the figure to which ax is connected.

Return type:

Figure

Notes

This works only for classes where the power method has effect_size, nobs and alpha as the first three arguments. If the second argument is nobs1, then the number of observations in the plot are those for the first sample. TODO: fix this for FTestPower and GofChisquarePower

TODO: maybe add line variable, if we want more than nobs and effectsize