statsmodels.base.model.LikelihoodModelResults.wald_test¶

LikelihoodModelResults.wald_test(r_matrix, cov_p=None, invcov=None, use_f=None, df_constraints=None, scalar=None)[source]¶

Compute a Wald-test for a joint linear hypothesis.

Parameters:¶

r_matrix{array_like, str, tuple}

One of:

array : An r x k array where r is the number of restrictions to test and k is the number of regressors. It is assumed that the linear combination is equal to zero.
str : The full hypotheses to test can be given as a string. See the examples.
tuple : A tuple of arrays in the form (R, q), q can be either a scalar or a length p row vector.

cov_parray_like, optional

An alternative estimate for the parameter covariance matrix. If None is given, self.normalized_cov_params is used.

invcovarray_like, optional

A q x q array to specify an inverse covariance matrix based on a restrictions matrix.

use_fbool

If True, then the F-distribution is used. If False, then the asymptotic distribution, chisquare is used. If use_f is None, then the F distribution is used if the model specifies that use_t is True. The test statistic is proportionally adjusted for the distribution by the number of constraints in the hypothesis.

df_constraintsint, optional

The number of constraints. If not provided the number of constraints is determined from r_matrix.

scalarbool, optional

Flag indicating whether the Wald test statistic should be returned as a sclar float. The current behavior is to return an array. This will switch to a scalar float after 0.14 is released. To get the future behavior now, set scalar to True. To silence the warning and retain the legacy behavior, set scalar to False.

Returns:¶

ContrastResults: The results for the test are attributes of this results instance.