6

# (8) _E = Aff_

where E is equivalent consumption, A is actual consumption, H is household size, and _e_ an equivalence scale elasticity [24]. Under the assumption that there no economies of scale, _e_ is set equal to 1, and equivalent consumption is simply per capita consumption. Under the assumption that two (or three, or four, of five,...) can live as cheaply as one, _e_ is set equal to 0, and equivalent consumption is simply aggregate household consumption. Although it is not uncommon to find to find _e_ set equal to one (the per capita adjustment), a more plausible position, at least in countries where a sizeable proportion of consumption is on non-food items, is that there are some economies of scale, but that the elasticity e is greater than zero. In their survey of equivalence scales in OECD countries, Buhmann et al. [24] found that most equivalence scales could be approximated quite closely by eqn (8) and that, on average, the implied value of the elasticity _e_ was around 0.4. Hentschel and Lanjouw (op. cit.), in their work on Ecuador, experiment with three values of _e:_ 0.4, 0.6, and 1.0. In what follows, we set _e_ equal to 0.5, which seems a reasonable intermediate position.

## MEASURING MALNUTRITION

Growth assessment is the single measurement that "best defines the health and nutritional status of children as disturbances in health and nutrition, regardless of their etiology, invariably affect child growth" [25]. Among various growth-monitoring indices, there are three commonlyused anthropometric measures that offer a comprehensive profile of malnutrition: stunting, underweight and wasting.

The term "stunting" is used to describe a condition in which children fail to gain sufficient height, given their age. Stunting is therefore an extremely low "height-for-age" (H/A) score. Stunting is often associated with long-term factors such as chronic malnutrition, especially protein-energy malnutrition, and sustained and frequent illness. It is therefore an indicator of past growth failure and is often used for long-term planing of policies and intervention programs in non-emergency situations. The term "underweight" is used to describe a situation where a child weighs less than expected, given his or her age. Underweight is thus an extremely low "weight-for-age" (W/A) score. Unlike height, weight fluctuates over time and therefore reflects current and acute as well as chronic malnutrition. The term "wasting" refers to a situation where a child has failed to achieve sufficient weight for height (W/H). Wasting often results from recent and continuing severe weight loss due to inadequate energy intake, recent and continuing poor health, or a combination of both.

The preferred reporting system of H/A, W/A and W/H is in terms of Z-scores<sup>3</sup> -_ a statistical measure of the distance from the median (mean) expressed as a proportion of the standard deviation. The most common cutoff point is -2Z-score, i.e., two standard deviations below the median values of the international reference. This is the cutoff risk level used to differentiate malnourished children from those adequately nourished. Children whose WA, W/A and W/1l scores fall below this point are therefore considered, stunted, underweight and wasted, 3Z - score =(Observed value) - (Median value of the referencevalue) Standard deviation of the reference population