Codes and Frequencies
MOD10FTP reports the time period (never, day, week, month, year) that sample adults used to describe the frequency of the light or moderate leisure-time physical activity that they engaged in. Prior to 2020, the survey text inquired specifically about exercise that lasted at least 10 minutes. This variable must be interpreted in conjunction with MOD10FNO, which reports the number of units corresponding to the time period in MOD10FTP. For example, a respondent who walks once a day would have a MOD10FNO value of 1 (to indicate 1 time) and a MOD10FTP value of 2 (which is the code for "day").
MOD10FWK, a recoded variable created by the staff at the National Center for Health Statistics, draws upon the information in MOD10FTP and MOD10FNO 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 Manual provides 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.
According to the Field Representative's Manuals for 2001-2018, the maximum frequency of each broad category of physical activity (moderate activity, vigorous activity, strengthening activities, and stretching activities) was topcoded at 4 times per day (or its equivalent in some other time unit). Beginning in 2020, individuals with values of 4 times per day (or its equivalent) were coded as "7 - Extreme value."
For further discussion of data collection on leisure-time physical activity in general for 1997 forward, see VIG10FNO (Frequency of vigorous activity 10+ minutes: Number of units).
MOD10FTP is available beginning in quarter 3 of 1997. For data on the frequency of respondents' light or moderate activity in the first half of 1997, see MOD20FTP2.
The question wording for MOD10FTP changed slightly in 2004.
For all years from 1997 forward, the survey section on physical activity began with the statement, "The next questions are about physical activities (exercise, sports, physically active hobbies ...) that you may do in your leisure time." Beginning in 2004, the question about frequency of light or moderate activities reiterated the point that respondents were only to report leisure-time activities. From 1997 through 2003, interviewers asked, "How often do you do light or moderate activities ..."; for 2004 forward, they asked, "How often do you do light or moderate leisure-time physical activities ..." Thus, beginning in 2004, the question wording made explicit what had previously been implicit and had been specified in the introductory statement only.
A second minor change to the survey question was instituted in 1999, when the form added the following instruction to interviewers: "If necessary, prompt with: How many times per day, per week, per month, or per year do you do these activities?"
This prompt gave explicit directions to interviewers on how to proceed if respondents gave a vague answer such as "quite often," "once in a while," or "hardly ever." However, while these directions were missing from the survey questionnaire before 1999, they were included in the Field Representative's Manuals for 1997-2000, which directed, "Prompt with 'How many times per day, per week, per month, or per year do you do these activities?'"
Furthermore, the 1997-2000 Manuals stated, "Always probe for an exact number. If the Sample Adult reports a range or interval, assist the Sample Adult in making an estimate by probing. For example, you might ask 'Could you give me a more exact number?'"
A third change to the questionnaire text in 2020 removed the requirement that the respondent reports activities only lasting at least ten minutes.
MOD10FTP is asked after MOD10FNO, which reports the number to be used in conjunction with the time units reported in MOD10FTP. Prior to 2020, the question for MOD10FNO stated, "How often do you do light or moderate leisure-time physical activities for at least 10 minutes that cause only light sweating or a slight to moderate increase in breathing or heart rate?" Beginning in 2020, the question simply asks, "How often do you do moderate-intensity leisure-time physical activities?" The question is preceded by a definition of moderate intensity activities as those that "cause moderate increases in breathing or heart rate whereas vigorous-intensity activities cause large increases in breathing or heart rate."
Finally, major questionnaire changes introduced in 2019 may affect comparability with earlier years. The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 1997: Sample adults age 18+ in quarters 3 and 4.
- 1998-2018: Sample adults age 18+.
- 2020: Sample adults age 18+.
- 1997-2018, 2020
- 1997-2018, 2020 : SAMPWEIGHT