statsmodels.stats.diagnostic.het_goldfeldquandt¶
-
statsmodels.stats.diagnostic.
het_goldfeldquandt
= <statsmodels.sandbox.stats.diagnostic.HetGoldfeldQuandt object>¶ test whether variance is the same in 2 subsamples
- Parameters
- yarray_like
endogenous variable
- xarray_like
exogenous variable, regressors
- idx
int
column index of variable according to which observations are sorted for the split
- split
None
orinteger
orfloat
in
intervall
(0,1) index at which sample is split. If 0<split<1 then split is interpreted as fraction of the observations in the first sample
- drop
None
,float
orint
If this is not None, then observation are dropped from the middle part of the sorted series. If 0<split<1 then split is interpreted as fraction of the number of observations to be dropped. Note: Currently, observations are dropped between split and split+drop, where split and drop are the indices (given by rounding if specified as fraction). The first sample is [0:split], the second sample is [split+drop:]
- alternative
str
, ‘increasing’, ‘decreasing’ or ‘two-sided’ default is increasing. This specifies the alternative for the p-value calculation.
- Returns
Notes
The Null hypothesis is that the variance in the two sub-samples are the same. The alternative hypothesis, can be increasing, i.e. the variance in the second sample is larger than in the first, or decreasing or two-sided.
Results are identical R, but the drop option is defined differently. (sorting by idx not tested yet)