gregRy - GREGORY Estimation

Functions which make using the Generalized Regression Estimator(GREG) J.N.K. Rao, Isabel Molina, (2015) <doi:10.3390/f11020244> and the Generalized Regression Estimator Operating on Resolutions of Y (GREGORY) easier. The functions are designed to work well within a forestry context, and estimate multiple estimation units at once. Compared to other survey estimation packages, this function has greater flexibility when describing the linear model.