For the earlier period, interviewers asked, "During the past 12 months (that is, since [date] a year ago), ABOUT how many days did illness or injury keep [person] in bed all or most of the day? (Include the days in the past 2 weeks.) (Include the days while a patient in a hospital.)" For the later period, interviewers asked, "During the past 12 months, (that is, since 12-month date a year ago), ABOUT how many days did illness or injury keep [person] in bed more than half of the day? (Include days while an overnight patient in a hospital.)" Comparability may be slightly compromised by the specification of "all or most of the day" versus "more than half the day" and "while a patient in a hospital" versus "while an overnight patient in a hospital."

Specifically, interviewers asked, "Was it more than 7 days or less than 7 days? Was it more than 30 days or less than 30 days? Was it more than half the year or less than half the year?" The values for BEDAYR2-- None, 1-7 days, 8-30 days, 31-180 days, 181-365--mirror the intervals mentioned in these follow-up questions.

Prior to 1997, one member of the household could answer this question for other household members (i.e., proxy reporting). Beginning in 1997, when the information was collected only for sample adults, individuals answered the question for themselves, except in rare cases when disability barred sample adults from responding. In general, self-reporting is more accurate than proxy reporting. Thus, researchers should be cautious about comparing results from BEDAYR from prior to 1997 to results from BEDAYR for 1997 forward, even if the analysis is limited to adults.