practical to use as a hand-scoring approach, and may be the method of choice in busy clin-
ical settings or in paper-and-pencil interview situations. As a result, the simple sum of the
scores of the items across all domains constitutes a statistic that is suff icient to describe the
degree of functional limitations.
Complex:  The more complex method of scoring is called “item-response-theory”
(IRT)–based scoring. It takes into account mu ltiple levels of diffic ulty for each WHODAS
2.0 item. It takes the coding for each item response as “none,” “mild,” “moderate,” “se-
vere,” and “extreme” separately, and then uses a computer to determine the summary
score by differentially weighting the items and the levels of severity. The computer pro-
gram is available from the WHO Web site. The scoring has three steps:
• Step 1—Summing of recoded item scores within each domain.
• Step 2—Summing of all six domain scores.
• Step 3—Converting the summary score in to a metric ranging from 0 to 100 
(where 0=no disability; 100=full disability).
WHODAS 2.0 domain scores. WHODAS 2.0 produces domain-specific scores for six
different functioning domains: cognition, mobilit y, self-care, getting along, life activities
(household and work/school), and participation.
WHODAS 2.0 population norms. For the population norms fo r IRT-based scoring of the
WHODAS 2.0 and for the population distribution of IRT-based scores for WHODAS 2.0,
please see www.who.int/clas sifications/icf/Pop_norms_distrib_IRT_scores.pdf.