Reporting of height and weight

In Wave 12 data on height and weight of respondents were collected, in order to calculate body mass index, a measure of adiposity. The aim of this experiment was to determine if the interview mode affect the accuracy of individuals’ responses on body weight and height.

Households in face-to-face modes (nurse and interviewer modes only, see the Section Mixed mode experiments: web and face-to-face, were randomly assigned to one of two groups for the collection of self-reported height and body weight: self-completion mode group and interviewer-administered group.

Nurse and interviewers assessed height and weight using the fieldwork protocols previously established in Understanding Society. Briefly height without shoes was measured using a portable stadiometer. Measurements taken with the respondents stretching to the maximum height and the head in the Frankfort plane. Weight was measured using a portable electronic scale. Respondents were asked to remove their shoes and any bulky clothing.

All web respondents were asked height and weight in the same way as those in the self-completion mode. Other than the mode, the questions were the same.

Allocation to this experiment was done at the household level; households were allocated randomly and equally to conditions (50% each). The variable controlling the treatment allocations is l_ff_height on record l_hhsamp_ip:

1          Self-reported height and weight in CAPI

2          Self-reported height and weight in CASI

The variables affected by this experiment are on record l_indresp_ip:

l_hlht, l_hlhtf, l_hlhti, l_hlhtc, l_hlwt, l_hlwts, l_hlwtp, l_hlwtk, l_hlwte, l_hlwtl