Key Concepts about the Physical Activity Questionnaire Data Files

Physical Activity Questionnaire Data Structure and Content

A physical activity questionnaire was used in NHANES from 1999 to 2006 to collect information on the frequency and duration of moderate- and vigorous-intensity physical activities engaged in for transportation, household chores, and leisure-time recreation during the previous 30 days. For respondents aged 2 to 11 years and 16 years and older, the questions were asked in the household interview. For respondents aged 12 to 15 years, the questions were asked as part of the Mobile Examination Center (MEC) interview. This approach was used to assist with the logistics of scheduling the household interview. Household interviews are by proxy for all questions for 12-15 years of age, except those related to physical activity. Scheduling young adolescents to answer only a short set of questions at the same time as the household proxy interview limited interview opportunities, therefore, youths 12-15 years old were asked the physical activity questions when they came to the MEC. The resulting data files can be analyzed to examine minutes per week for all reported physical activity combined, or by type.

The data are provided in two files – PAQ and PAQIAF – found on the Questionnaire page for each NHANES 2-year cycle. Notably, none of the data were imputed.

Physical Activity Questionnaire

File Name: PAQ
Data Contained in the Data File

• Participation in active transportation (Yes/No)
• Active transportation sessions per day, week, or month
• Minutes of active transportation per day
• Participation in moderate- and vigorous-intensity household activity (Yes/No)
• Household activity sessions during the past 30 days
• Minutes of household activity per session
• Participation in vigorous leisure-time physical activity (Yes/No)
• Participation in moderate leisure-time physical activity (Yes/No)
• Participation in muscle-strengthening activity (Yes/No)
• Muscle-strengthening activity sessions during the past 30 days
• Hours of screen time per day (TV-, computer-, and video-use)
• Hours of television on the day before interview
• Hours of computer use on the day before interview
• Self-rated current activity level for usual daily activities
• Self-rated activity level compared to self 1 year ago
• Self-rated current activity level compared to self 10 years ago
• Self-rated current activity level compared to others of same sex and age
• Participation in exercise, sports, or physically active hobbies (Yes/No)

Physical Activity Individual Activities File

File Name: PAQIAF
Data Contained in the Data File

• Detailed description about each leisure-time activity reported including type, intensity, sessions during the past 30 days, minutes of activity per session and MET level

Be aware that the first file, PAQ, contains a single record per person. This record includes responses to all the questions in the questionnaire, except frequency and duration of specific recreational activities reported. The PAQ file does include the response (Yes/No) regarding whether the respondent engaged in any exercise, sports, or physically activity hobbies.

The second file, PAQIAF, contains one record for each recreational activity reported.  Therefore, it contains one or more records per person.  This difference is illustrated below. These files can be linked by sequence number (SEQN), the variable that identifies individual NHANES participants. Data from both PAQ file and PAQIAF are needed to create indicators of total physical activity.

Example of PAQ Single Record Output

PAQ Activity Variables

	PAQ100	PAD120	PAD160	PAD200	PAD320	PAD440
Description	Tasks around home/yard past 30 days	# of times past 30 days	How long each time	Vigorous activity over past 30 days	Moderate activity over past 30 days	Muscle strengthening activities over past 30 days
Code	1 – Yes 2 – No		(minutes)	1 – Yes 2 – No	1 – Yes 2 – No	1 – Yes 2 – No

Example of PAQ Single Record Output

SEQN ID	PAQ100	PAD120	PAD160	PAD200	PAD320	PAD440
31131	1	9	60	2	2	2
31132	1	9	60	2	1	2
31134	1	30	120	2	1	2
31136	1	9	180	1	1	2
31139	1	4	25	1	1	1

 

Example of PAQIAF Multiple Record Output

PAQIAF Activity Variables

	PADACTIV	PADLEVEL	PADTIMES	PADDURAT	PADMETS
Description	Leisure time activity	Activity level	# of times did activity in past 30 days	Average duration of activity	MET score for activity
Code	(code)	1 – Moderate 2 – Vigorous		(minutes)

Example of PAQIAF Multiple Record Output

SEQN	PADACTIV	PADLEVEL	PADTIMES	PADDURAT	PADMETS
31132	19	1	20	240	3.5
31132	42	1	13	40	3.5
31134	42	1	13	30	3.5
31136	40	1	13	30	4.5
31136	10	2	9	60	7.0
31139	10	1	30	15	5.0
31139	43	1	30	10	3.0
31139	29	2	30	10	10.0
31139	36	2	30	10	8.0
31139	40	2	30	30	7.0

 

Be aware that the PAQ file has records for all survey participants, whether they answered the physical activity questions or not.  On the other hand, the PAQIAF contains records only for participants who reported any vigorous or moderate leisure time physical activity (VARIABLE=PAD200, PAD320). Therefore, individuals will have a record in the PAQ file even if they have no records in the PAQIAF. For example, looking again at the sample outputs above, SEQN 31131 is found in PAQ but not in PAQIAF because the individual did not report specific moderate or vigorous activity.