Date Added: Aug 2009
To analyze the effect of health on work, many studies use a simple self-assessed health measure based upon a question such as "Do you have an impairment or health problem limiting the kind or amount of work you can do?" A possible drawback of such a measure is the possibility that different groups of respondents may use different response scales. This is commonly referred to as "Differential Item Functioning" (DIF). A specific form of DIF is justification bias: to justify the fact that they don't work, non-working respondents may classify a given health problem as a more serious work limitation than working respondents.