Codes and Frequencies
MOD20FTP reports the time period (never, day, week, month, year) that respondents used to describe the frequency of their light or moderate physical activity that they engage in for at least 20 minutes. This variable must be interpreted in conjunction with MOD20FNO, which reports the number of units corresponding to the time period in MOD20FTP. For example, a respondent who walks once a day would have a MOD20FNO value of 1 (to indicate 1 time) and a MOD20FTP value of 2 (which is the IPUMS NHIS code for "day").
MOD20FWK, a recoded variable created by the staff at the National Center for Health Statistics, draws upon the information in MOD20FTP and MOD20FNO and reports the frequency of light or moderate leisure-time physical activities in terms of a single time unit, times per week.
Light or moderate activities are described in the survey question itself as activities that "cause only light sweating or a slight to moderate increase in breathing or heart rate." The Field Representative's Manuals for 1997 forward provide examples of light or moderate leisure-time physical activities, although these examples were not routinely shared with respondents. These examples include leisurely walking or bicycling, slow swimming or dancing, and simple gardening.
MOD20FTP is only available for 1997 and is provided to allow comparability across all quarters of that year.
During the first half of 1997, due to an error of the wording of the survey question, respondents were asked how frequently they engaged in physical activities lasting a minimum of 20 minutes. This mistake was corrected beginning in quarter 3 of 1997, when the minimum duration of physical activity was lowered to 10 minutes.
To allow analysis of light or moderate leisure-time physical activity across all quarters of 1997, the National Center for Health Statistics created "transitional" variables (such as MOD20FTP) that cover all quarters of 1997.
These transitional variables combined the data on light or moderate leisure-time physical activity for at least 20 minutes from quarters 1 and 2, with data from the subset of respondents in quarters 3 and 4 who engaged in light or moderate leisure-time physical activity for at least 20 minutes. In other words, the transitional variables for 1997 allow comparability across all quarters of 1997 only by excluding respondents from quarters 3 and 4 whose physical activity lasted between 10 and 19 minutes (i.e., less than 20 minutes in duration). Researchers who wish to analyze data on light or moderate physical activity (for 20+ minutes) for all quarters of 1997 can use these transitional variables. For the full list of these transitional variables, which cover 1997 only and are restricted to adults who did light or moderate exercise for at least 20 minutes, see MOD20FNO.
Researchers who wish to analyze data from multiple years on adults' light or moderate leisure-time physical activity should restrict their data from 1997 to quarters 3 and 4 and use variables beginning with "MOD10."
See VIG10FNO for an overview of the variables relating to adults' leisure-time physical activity for at least 10 minutes for the third quarter of 1997 forward.
- 1997: Sample adults age 18+. (For quarters 3 and 4, persons who reported a duration of 10-19 minutes of vigorous activity are excluded.)
- 1997 : SAMPWEIGHT