Statistics
 

Food security methodology

The 1996 World Food Summit (WFS) called to reduce the number of undernourished people by half by 2015. In 2000, the Millennium Declaration (MD) recognized the value of hunger and poverty reduction by setting the MDG target of “halving, between 1990 and 2015, the proportion of people who suffer from hunger” (target 1.C).

Monitoring progress
For the purpose of monitoring progress towards the WFS and the MDG1 targets, FAO provides regular updates on the number and proportion of population below the minimum level of dietary energy requirement (MDG indicator 1.9). Such estimates, produced at global, regional and country levels, are presented annually in the State of Food Insecurity in the World (SOFI) report.

Methodological framework
FAO defines undernourishment as a situation of “continued inability to obtain enough food”, and the Prevalence of Undernourishment (PoU) as the “probability that an individual randomly selected from a population is found to be undernourished”. The intake adequacy is evaluated with reference to a normative benchmark – the dietary energy requirement – established by nutritionists.

Although it is not viable to assess precisely the individual dietary energy requirement, it is possible to make an inference at the population level in probabilistic terms. Indeed, the FAO methodological framework for estimating the prevalence of undernourishment makes reference to:

i) a probability distribution of the possible levels of the habitual individual yearly Dietary Energy Consumption of a representative individual in a population; and
ii) a cut-off point for intake adequacy (MDER) relevant for the same population.

In 2011-12 the FAO methodology for estimating the prevalence of undernourishment went through a scrupulous review, intended to identify the most appropriate model to describe the habitual dietary energy consumption in the population and to improve the estimation of its parameters. The estimates published in State of Food Insecurity in the World 2012 report are the result of this revision.

Parameters and revisions

• Since 1996 (WFS), the distribution of dietary energy consumption in the population has been assumed to be log-normal. One of the main methodological changes that FAO introduced in 2012 is the adoption of a skew-normal distribution, which is fully characterized by three parameters: the mean, the coefficient of variation (CV) and the skewness. The skew-normal distribution, which is more flexible than the log-normal, better accounts for changes in the degree of asymmetry associated with changes in food consumption.

• The mean of the distribution is given by the Dietary Energy Supply (DES) and is derived from the Food Balance Sheets, which are regularly prepared by FAO and available for nearly all countries. In 2012 the Statistics Division published new estimates of DES and revised the historical series backwards.

• The CV and skewness are derived from available National Household Surveys (NHS) that collected data on both food consumption/acquisition and income. This year, thanks to the collaboration between FAO and National Statistical Offices, the Statistics Division has updated the CVs and estimated the skewness of the food consumption data distributions. Approximately 50 surveys were processed at FAO Headquarters and new parameters were obtained for about 40 countries that, together, cover almost 70 percent of the number of undernourished in the developing world.

• The cut-off point for intake adequacy is estimated according to the normative standards set forth in the 2001 FAO/WHO/UNU Expert Consultation. To minimize the probability of overestimating undernourishment, the FAO method uses the minimum of the range of values consistent with adequate nourishment (ie., the lowest acceptable body weight for a given height, and light activity). The cut-off point for a population is derived by aggregating sex and age specific MDERs using the proportion of the population in the different sex and age groups as weights. Since the sex-age distribution of the population changes over time, the cut-off point is updated every year to reflect the change in the demographic structure of the population. New data on human stature were used in 2012, with a substantial revision of the population size and structure obtained by the latest revision of world population estimates (UN 2010).

• Food losses occurring at the retail level have also been introduced for the first time this year. Country specific values regarding the average per capita loss of calories have been estimated taking into account data provided by a recent FAO study on food losses at various stages of the commodity chain.