QBAL computes respondent-level weights to match a sample to a population on the marginal proportions of multiple variables simultaneously, a process often called "Sample Balancing."  

QBAL uses Deming's Iterative Proportional Fitting (IPF) method with algorithms that are limited only by the total number of variable points rather than the numbers of possible cells or of cases balanced. This allows very large samples to be balanced quickly on a large number of variables.  

The QUIP specification language allows for infinitely complex variable definitions. Samples can be projected to any population size and input data sets with pre-existing weights may be used, allowing for multi-stage as well as multi-variable weighting.

Copyright 1999-2006 Jan Werner Data Processing - Last modified: February 16, 2001