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METVALUE
Metabolic equivalent (MET) value for activity codes

Codes

METVALUE is a 4-digit numeric variable with 2 decimal places. Each 6-digit activity code is assigned a metabolic equivalent value, except for 50xxxx codes.
999.98 = Not available

Description

METVALUE reports the metabolic equivalent (MET) value associated with ATUS primary activity codes. This is an activity-level variable.

METVALUE as explained in this more extensive documentation is derived from the 2000 Compendium of Physical Activities.

Each METVALUE is computed by aggregating and averaging MET values associated with lexicon example activities for each 6-digit activity level. For example, personal care (020000) consists of grooming (010200), which in turn includes activities such as sleeping (010101) and washing, dressing, and grooming (010201). Washing, dressing and grooming (010201) includes activities such as doing own hair (which is listed as an example of washing, dressing, and grooming) and is associated with a MET value of 2.5. This 2.5 MET value is obtained from the Self-Care (13) major activity with specific activity Hairstyling (13045) under the 2000 Compendium. MET values for all the lexicon examples under 010201, in this case, get aggregated and averaged to obtain the MET value of 2.10 for the 010201 activity at the 6-digit code. N.e.c (Not elsewhere classified) 6-digit codes, for example Personal Care n.e.c (019999), are obtained from aggregating and averaging all MET values related to 6-digit activity codes within each major activity such as Personal Care. Please see additional documentation for detailed methods used to compute the MET values. Tudor-Locke et al. (2009) explain that the ATUS intensity levels are not intended to measure energy costs of physical activity for individuals but mostly should be used to identify time spent in activities by type and intensity.

METVALUE associated with Work (050001 and 050002) is derived from an extensive and iterative process of averaging MET values for all 22 occupational categories (OCC2 and OCC2_OJ_CPS8) and based on the 2002 Census Occupation Codes. Other work and work-related activities are derived from the general algorithm described above.

METVALUE associated with Traveling (180000) is obtained using WHERE.

ATUS-X has used the same methods employed by Tudor-Locke et al. (2009) to generate METVALUE associated with 2004+ activities. See the ATUS-X documentation and accompanying excel file detailing the methods and results.

Please note that although we have replicated the methodology used by Tudor-Locke and colleagues to assign MET values to activities, caution is needed. These MET values may not represent energy expenditures for three reasons: First, many of the categories aggregate activities with vastly different potential levels of energy expenditures; the MET values for all the activities in the category are simply averaged assuming equal weights whereas some of the activities (and, therefore, the MET) may be rare. Second, the MET values for many of the activities have not been validated in the scientific literature through accelerometry or other scientific methods that accurately measure energy expenditures. The Compendium of Activities calls these "estimated" values. Third, over the period in which an activity is reported, substantial variation in energy expenditure may occur. These issues will be more problematic the more frequent and the more diverse are the specific activities included in a category, such as higher levels of aggregation and "other" catchall categories, and the longer the duration. One specific example is the category 020603 -- walking, exercising, playing with animals -- which aggregates activities with MET values ranging from 3.0 to 5.0. The overall MET average is 3.8. In the Compendium of Physical Activities only one of these MET values for activity is supported in the published literature -- the 3.0 for walk/run, playing with animals, general, light effort, only active periods. The other MET values are "estimated." For more information about this issue see the Tudor-Locke et al (2009).

This variable is available via extracts that are hierarchical or rectangular (activity) (more info on extract formats). If you request a hierarchical extract and plan to construct time use variables in your statistics package, this variable may be useful to you. If you request a rectangular extract and plan to construct time use variables through the extract system, METVALUE will not be included in your extract, as persons are the unit of observation for rectangular extracts rather than activity or who records.

Comparability

The activity coding lexicon has changed over time, but Tudor-Locke et al. (2009) find that MET values should be minimally affected by these changes (within 0.74 METs for 2003-2005 changes).

Universe

  • All activities.

Availability

  • 2003-2017

Flags

This variable has no flags.