An exchangeable working dependence structure.
|covariance_matrix(expval, index)||Returns the working covariance or correlation matrix for a given cluster of data.|
|covariance_matrix_solve(expval, index, ...)||Solves matrix equations of the form covmat * soln = rhs and returns the values of soln, where covmat is the covariance matrix represented by this class.|
|initialize(model)||Called by GEE, used by implementations that need additional setup prior to running fit.|
|update(params)||Updates the association parameter values based on the current regression coefficients.|