The Field Representative's Manuals for 2001 forward noted that "number of school days missed" was part of a survey section relating to "the general health status of the child." The documentation for 1997 forward provided interviewers with no definition of "school" and no guidance on what constituted a school loss day due to illness or injury.

The Manuals for 1981 and 1988 provided slightly more guidance when discussing school loss days for children over the past year:

Much clearer directions came from an earlier question, asked for all children age 6 to 16 (in 1981) or age 5 to 17 (in 1988), that had collected information about school loss days during the past two weeks (see SLDAY2WK). The 1981 and 1988 Manual text related to this earlier question supplied formal criteria for defining a "school-loss day" (though this information was not necessarily shared with respondents):

In 1981 and 1988, the question about year-long school loss days was directly preceded by inquiries about school attendance and grade level. Here, in both years, interviewers were directed to count only "regular school." According to the Manuals for 1981 and 1988, if responses indicated that "the child is attending a nonregular school (that is, vocational, trade, or business schools outside the regular school system)," interviewers were directed, "re-ask the question emphasizing that we are interested in regular schools."

The definition of a "regular school" was somewhat different in 1981 and 1988, however. The 1981 Manual directed, "For this section, also consider attendance at nursery school or kindergarten as 'Going to school.'" By contrast, the 1988 Manual asserted, in the same context, "nursery school and preschool are not regular schools."

For 1997 forward, "school" attendance and school loss days due to illness or injury were entirely respondent defined, with no directions provided to interviewers. The related variable about school loss day in the past 2 weeks, SLDAY2WK, was discontinued after 1996 and thus provided no definitions relevant to SLDAYR for 1997 and later years.

In 1981 and 1988, answers were top-coded at 98+ school loss days, while for 1997-2017, responses up to 240 days (the legal length of a school year) were allowed. Beginning in 2018, responses were top-coded at 40 days.