Methodological issues using household budget survey expenditure data for individual food availability estimation: Irish experience in the DAFNE pan-European project

Abstract Objective Irish participation in the EU-supported DAta Food NEtworking (DAFNE) project required compliance with the overall aims and objectives. The Irish Household Budget Survey (HBS) expenditure data had to be transformed into a format compatible with the collaborative effort, by converting them into quantities of foodstuffs available per person per day. Setting The Irish 1987 HBS expenditure data on all commodities for 7705 households in the Republic of Ireland, collected using a 14-day diary kept by all members of the household aged 15 years and over. Design Following identification of 188 food items in the HBS dataset, retail prices per unit weight were sought for each food. Adjustment of prices, collected from a number of different sources, was made to those of 1987 using the Consumer Price Index. Simple models were used to estimate household food availability through application of the adjusted retail prices per unit weight to the expenditure data. The household level data were converted to food availability per person per day. An internal validation of quantities estimated using the retail prices was made using the 12 foodstuffs for which the Irish HBS collects expenses and quantities. Results The comparison of quantities published by the Irish Central Statistics Office for 12 foodstuffs in the Irish 1987 Household Budget Survey with the quantities estimated using equivalent expenditure data and corresponding retail prices showed agreement, with less than a 10% margin of error for 10 of the foods. Conclusion In spite some difficulty in converting HBS food expenditure data into food availability per person per day, the DAFNE approach is potentially useful for Irish nutrition surveillance purposes and for facilitating comparisons of the Irish HBS food data with those of other European countries.