For each wave of the Food and You 2 survey, weights were calculated with two objectives in mind: to compensate for known differences in sample member selection probabilities; and, to reduce non-response bias through post-stratification. Separate samples were selected in England, Wales and Northern Ireland and Individual country weights were calculated which equalised weighted and unweighted sample totals for each country. Additional all-country weights, which weighted sample numbers in each country in proportion to country population estimates were also calculated. An additional weight was calculated with the sole purpose of aligning selected demographic characteristics of the English sample to those of the Welsh sample. This was termed the ‘Welsh England’ weight. Weighting complications arose because, in each wave, not all questions were asked of all sample members. In most waves questions were asked either of: all sample members, or online respondents only (i.e. the questions were excluded from all postal questionnaires), or online respondents and half (randomly selected) of postal questionnaire respondents. There were also some additional complications in wave 3 when a small number of questions were fielded by different modes in different countries. Because of this in each wave several weights, depending on mode of administration, were calculated (i) for each country (ii) all countries combined and (iii) for ‘Welsh England’ estimates.
F&Y2 trends weighting note: Calculation of trend weights
Objective
Investigators
Patten Smith; Kathryn Gallop; Kelly Ward; Hannah Harding
Institution
Ipsos
Funding Source
Project number
FS430662