linearmodels.system.covariance.HomoskedasticCovariance

class HomoskedasticCovariance(x, eps, sigma, full_sigma, *, gls=False, debiased=False, constraints=None)[source]

Homoskedastic covariance estimation for system regression

Parameters
xList[ndarray]

List of regressor arrays (ndependent)

epsndarray

Model residuals, ndependent by nobs

sigmandarray

Covariance matrix estimator of eps

glsbool

Flag indicating to compute the GLS covariance estimator. If False, assume OLS was used

debiasedbool

Flag indicating to apply a small sample adjustment

constraints{None, LinearConstraint}

Constraints used in estimation, if any

Notes

If GLS is used, the covariance is estimated by

\[(X'\Omega^{-1}X)^{-1}\]

where X is a block diagonal matrix of exogenous variables. When GLS is not used, the covariance is estimated by

\[(X'X)^{-1}(X'\Omega X)(X'X)^{-1}\]
Attributes
cov

Parameter covariance

cov_config

Optional configuration information used in covariance

sigma

Error covariance

Methods

Properties

cov

Parameter covariance

cov_config

Optional configuration information used in covariance

sigma

Error covariance