The within term carries the factor m/M, so it vanishes when every PSU is taken – the check that the bookkeeping is right.
Value
List with estimate, se, ci_lower,
ci_upper, psu_mean, psu_var,
between_term, within_term, m, M,
N.
Details
Formula: Yhat = sum_l N_l ybar_l / sum_l N_l; V = (M/N)^2 [ ((M-m)/M)/(m(m-1)) * sum (N_l ybar_l - N_l Yhat)^2 + (1/(mM)) * sum N_l^2 ((N_l-n_l)/N_l) s_l^2 / n_l ]
References
Cochran (1977), Sampling Techniques, 3rd edition, Chapter 10 (subsampling / two-stage sampling). Chapter 10 was NOT in the scanned excerpt available to this batch, so the estimator and variance are taken from the reference implementation in the CRAN package samplingbook 1.2.4, function submean with method = "ratio".
