Calibration for nonresponse treatment: In one or two steps?

This paper explores the different ways in which auxiliary information can be put to use in calibrated weighting adjustment under survey nonresponse. Information is often present at two levels, the population level and the sample level. The many options available in executing the calibration derive from several factors: One is the order in which the two sources of information enters into calibration, a choice of a bottom-up as opposed to a top-down approach. Another is whether the calibration should be carried out sequentially in two steps, or in one single step with the combined information. A third question is whether one can simplify the procedure, at no major loss of accuracy, by transcribing individual population auxiliary data from the register to the sample units only. We make a systematic list of the possibilities arising for calibration adjustment in this setting. An empirical study concludes the paper.