<prompt> Most impoant epidemiological tool used for assessing disability in children is -Activities of Daily Living ADL scaleWings Handicaps, Behaviour and skills HBS ScheduleBinet and Simon IQ testsPhysical Quality of Life Index PQL 1  <response>: Measurement of disability There have been many attempts to measure or record in standardized form the aspects of behaviour, psychological functions and social performance. One of the most impoant is Wings Comprehensive Handicaps, Behaviour and Skills Schedule HBS which has been used in epidemiological studies to assess the total child population in terms of detailed scales of specific abilities and disabilities. Results from these surveys have raised impoant questions about ethnic differences in disability profiles, individual programme planning, defining new syndromes of disability and the possibilities of new parameters for classification. The HBS is essentially a research tool, but Wing has developed from it a small practical schedule for use in service contexts using what had emerged as the most impoant aspect of mobility, communication and social interaction. The resulting Disability Assessment Schedule DAS is being used in several communities as a source of high quality routine data for total population Ref: Park 25th edition Pgno : 717 