HDDS

Household Dietary Diversity Score (HDDS)

The household dietary diversity score is designed to reflect a household’s access to a variety of foods by providing a qualitative measure of household food consumption. Therefore, HDDS is a proxy measure of the socio-economic level of the household. The reasons HDDS is an attractive proxy indicator are as follows:

A more diversified diet is itself an important outcome
A more diversified diet is associated with improved outcomes in areas such as birth weight, child anthropometric status and increased haemoglobin concentrations
A more diversified diet is highly correlated with caloric and protein adequacy, the intake of higher quality protein, and household income
Dietary diversity can be potentially examined at household and intra-household levels
Obtaining data to calculate the HDDS is relatively straightforward and it typically takes less than 10 minutes per respondent to complete an HDDS questionnaire

In order to calculate the HDDS, foods are classified into 12 different food groups. This is done to better reflect the quality of diet as the number of different food groups consumed rather than the number of different foods consumed is calculated. A larger number of food groups in one’s diet implies a higher probability that their diet offers more diversity in macro- and micronutrients.

Though the HDDS questionnaire is user-friendly and can thus be rapidly and easily administered, the score does not provide information on dietary diversity at the individual level. Users give a simple count of food groups that the household consumed in the previous 24hr period. As a general rule, foods consumed outside the household that were not prepared in the home are not usually included.

In general, an increase in household dietary diversity reflects an improvement in the household’s diet as the increase in the average number of different groups consumed provides a quantifiable measure of improved household food access. However, to use this indicator to assess improvements in food security, the HDDS must be compared to a meaningful level of diet diversity. Unfortunately, normative data on ‘ideal’ target levels of diversity are usually unavailable. To work around this two options can be used to determine appropriate targets.

Option 1: Dietary diversity patterns of the wealthier households surveyed can be used as a target under the assumption that as incomes rise, poorer households will diversify their food expenditures and thereby, follow the consumption patterns of the wealthier households. If income data is available, the sample can be divided into terciles of income (three income groups) with the HDDS target established as the average dietary diversity calculated for the richest income tercile. If income data is unavailable, income groups can be defined using proxies such as the possession of assets or any other items found to be highly correlated with income in the project population.

Option 2: In the absence of income or economic data, a HDDS target can be established by taking the average diet diversity of the upper tercile of diversity (33 percent of households with highest diversity).

Both of these options have the advantage that the target set represents a level of dietary diversity that is demonstrably achievable by the sample population.

To calculate the HDDS score, the following formula is applied.

It is important to note that HDDS and Food Consumption Score (FCS) are highly correlated and therefore, can be used interchangeable as a measure of household-level diet diversity and as a validated proxy for energy sufficiency in most contexts. However, neither of these indicators can be used as a proxy for micronutrient adequacy as they have not been validated against gold standard measures of micronutrient adequacy.

In addition, when using both the FCS and HDDS, one faces the challenge of determining how to capture and whether to exclude small amounts of food. For both indicators, the accuracy to predict caloric adequacy increases by ensuring small items consumed in small amounts are excluded. Furthermore, both FCS and HDDS are not sensitive to intra-household inequities in food consumption and thus are not to be used in interventions targeting specific population groups such as nutritionally vulnerable women or children.

Since HDDS and FCS provide very similar information, the selection of one of the indicators over the other can often be driven by institutional preference (if an organisation or individual is interested in comparing their results to those of a WFP survey then FCS is preferable) or by the need for comparability with other surveys (if there is need to compare with other surveys that previously used HDDS then HDDS is preferable).