GNU R analysis of complex survey samples

 Summary statistics, two-sample tests, rank tests, generalised linear
 models, cumulative link models, Cox models, loglinear models, and
 general maximum pseudolikelihood estimation for multistage stratified,
 cluster-sampled, unequally weighted survey samples. Variances by Taylor
 series linearisation or replicate weights. Post-stratification,
 calibration, and raking. Two-phase subsampling designs. Graphics. PPS
 sampling without replacement. Principal components, factor analysis.