SAMPLING METHOD OF THE 1998 NORWEGIAN TRAVEL SURVEY: AN ANALYSIS OF ESTIMATOR PROPERTIES USING WESVAR
Ronny Klæboe, B Grue · 1999
An ad hoc two stage cluster sampling scheme used for the National Travel Survey in 1998 has not previously been documented. The sampling scheme consists of a simple random sample of households from a national telephone directory, whereafter the person over 13 years of age and that last celebrated a birthday is selected. The sampling fraction at the second stage is thus inversely proportional to cluster size causing simple sample means to be biased estimators for their respective population means. This document shows the size of the bias to be substantial but ratio to size estimators can be used instead. In addition to the weighting for household size the datafile is however also weighted with county data in order to take advantage of the improved precision provided by the inclusion of data from three regional samples.