Protocol - Hip Circumference - Hip Circumference

The following protocol was taken from the Third National Health and Nutrition Examination Survey (NHANES III).The measurement is recorded to the nearest 0.1 cm.

The Expert Review Panel (ERP) recommends that researchers view the NHANES III video for anthropometric measures. The video includes a measure called Buttocks Circumference that is also hip circumference: http://www.cdc.gov/nchs/video/nhanes3_anthropometry/circumference/circumference.htm.

Notes from ERP:

The notion of recommending replicate measurements comes from the reduction in random errors of measurement and accompanying improved measurement reliability when the mean of multiple measurements is used rather than a single measurement. This improvement in measurement reliability, however, depends on the reliability of a single measurement in the hands of the data collectors in a particular study (Himes, 1989). For example, if a measure like recumbent length in a given study has a measurement reliability of 0.95 (expressed as an intraclass correlation coefficient), taking a second measurement and using the mean of the two in analyses will only improve the reliability to 0.97, yielding only a 2% reduction in error variance for the additional effort. If, in the same study, the reliability of a single triceps skinfold measurement was 0.85, using the mean (including a replicate measurement) would raise the reliability to 0.92 and yield a 7% reduction in error variance, a more than three-fold improvement compared with recumbent length. The intraclass correlation coefficient is specifically recommended here for assessing reliability because it takes account of both random and systematic errors of measurement, whereas the interclass correlation (e.g., Pearson correlation) takes account of only random errors of measurement.

Because the benefits of taking replicate measurements are so closely linked with the existing measurement reliability, it is recommended that as a part of the training of those who will be collecting anthropometry data, a reliability study be conducted that will yield measurement reliability estimates for the data collectors, protocols, settings, and participants involved in that particular study (Himes, 1989). If the measurement reliability for a single measurement is ≥ 0.95, the recommendation is that replicate measurements are not necessary and will yield little practical benefit. If the measurement reliability is < 0.95, the recommendation is to include replicate measurements as prescribed.

If replicate measurements are indicated because of relatively low reliability, a second measurement should be taken, including repositioning the participant. A third measurement should be taken if the first two measurements differ by > 0.5 cm. If it is necessary to take a third measurement, the two closest measurements are averaged. Should the third measurement fall equally between the first two measurements, all three should be averaged.