HTvar                   Variance of the Horvitz-Thompson estimator
jipApprox               jipApprox: Approximate inclusion probabilities
                        for survey sampling
jipDFtoM                Transform a Joint-Inclusion Probability
                        data.frame to a matrix
jipMtoDF                Transform a matrix of Joint-Inclusion
                        Probabilities to a data.frame
jip_MonteCarlo          Approximate inclusion probabilities by Monte
                        Carlo simulation
jip_approx              Approximate Joint-Inclusion Probabilities
