http://whqlibdoc.who.int/hq/2001/a78634.pdf

This study is to determine whether existing data sources from household interview based surveys conducted in a large number of countries may be used towards estimating the distribution and levels of severity of non-fatal health at the population level. Operationally, this objective addresses two main questions: 1. Is there information content on the severity and distribution of non-fatal health status in data collected through household interview surveys? 2. May this information be compared in a valid and reliable manner across countries?