Individual Dietary Diversity Score (IDDS)
English: the average number of different food groups consumed by [specify the target group] the previous day and night
French: le nombre moyen des différents groupes d'aliments consommés par [préciser le groupe cible] le jour et la nuit précédents
Portuguese: número médio dos diversos grupos alimentares consumidos pelo [especifique o grupo-alvo] no dia e noite anteriores
Czech: průměrný počet potravinových skupin zastoupených v jídle konzumovaném [určete cílovou skupinu] během uplynulého dne a noci
What is its purpose?
The indicator assesses the number of (pre-determined) food groups which were eaten by a specific target group the previous day or night. IDDS is most commonly used for children 6-23 months of age and for children 24-59 months of age but it can also be used for adults. It is an indicator of a diet's micronutrient adequacy, an important dimension of its quality. It does not measure the intake of kilocalories.
How to Collect and Analyse the Required Data
Collect the following data by conducting individual interviews with a representative sample of your target group members (if you assess children's IDDS, interview their mothers or other primary caregivers responsible for feeding the children).
1) Check whether yesterday was a special day (religious festival or celebration) when an unusually varied or limited diet was eaten - if so, do not proceed with collecting dietary data as it is likely that they will not reflect a typical diet.
2) List all meals which the person ate in the previous day in the Recording Meals Form (see link below).
3) Double check the meals' composition (e.g. porridge with or without milk).
4) Check for any snacks (including fruits) which were not mentioned.
5) Only then record in the questionnaire which food groups were eaten. Double check with the respondent regarding which foods the child or the adult ate from groups that were not mentioned (for example: "Did s/he yesterday eat any eggs?")
6) Count the number of consumed food groups (i.e. the Individual Dietary Diversity Score).
7) Calculate the indicator's value by summing up all IDD scores and dividing them by the number of respondents.
Disaggregate the data by age group, gender, and the household's wealth category.
1) Individual dietary diversity is prone to seasonal differences. Do your best to collect baseline and endline data in the same period of a year; otherwise it is very likely that they will not be comparable. Do not collect data during the fasting periods (such as pre-Easter time or Ramadan) and during the fasting days.
2) This indicator relies on accurate age assessment. Since people often do not remember the exact dates of their children’s birth, the data collectors should always verify the child’s age. This can be done by reviewing the child’s birth certificate, vaccination card or another document; however, since many caregivers do not have such documents (and since they can include mistakes), it is essential that your data collectors are able to verify the child’s age by using local events calendars. Read FAO’s Guidelines (see below) to learn how to prepare local events calendars and how to train data collectors in their correct use.
3) IDDS works with 8 food groups for children 6-23 months of age, and 9 food groups for children 24-59 months of age, older children and adults - for details, see WHO guidance below. Note that the original WHO 2010 guidance provided below works with 7 food groups for children 6-23 months of age; however, based on a June 2017 expert consultation it has been updated to reflect the inclusion of breast milk as an 8th food group. For details regarding this change, see WHO/UNICEF (2017) Operational Guidance provided in the documents below.
4) Record food groups in the questionnaire only after all meals were listed in the Recording Meals Form – never record it straightaway as it is very likely that the number of food groups consumed will be under-reported.
5) When training your data collectors, practice extensively which meals belong to which food group (allocate at least 3 hours full of examples and exercises). For example, while pumpkin flesh belongs to Vitamin A Rich Foods, pumpkin leaves belong to Dark Green Leafy Vegetables (see more examples in the FAO Guidelines below). If your questionnaire includes examples of different foods per each group, adjust them to the local context.
6) Do not record foods in quantities lower than one tea spoon (for example, a small amount of fish powder added for flavouring).
7) Well-designed, long-term (3 years or more) projects have a chance to increase the average IDDS by 1 score; for short-term projects, an increase by 0.5 score is a realistic maximum you can achieve.
8) Based on the number of meals included in the Recording Meals Form, you can also assess the meal frequency. Combination of IDDS + meal frequency data enables you to determine the percentage of children which consume a Minimum Acceptable Diet (see separate page on MAD indicator).
9) Take advantage of the very useful guidelines written by FAO and WHO - access below.
Access Additional Guidance
- FAO (2013) Guidelines for Measuring Household and Individual Dietary Diversity (.pdf)
- PIN (2015) Practical Checklist for Conducting Nutrition Surveys (.pdf)
- FAO (2008) Guidelines for Estimating the Month and Year of Birth of Young Children (.pdf)
- PIN (2014) Recording Meals Form for Assessing Dietary Diversity - Adults (.docx)
- PIN (2014) Recording Meals Form for Assessing Dietary Diversity - Children (.docx)
- WHO (2010) Indicators for Assessing IYCF Practices Part 2: Measurement (French version) (.pdf)
- WHO (2010) Indicators for Assessing IYCF Practices Part 2: Measurement (English version) (.pdf)
- WHO/UNICEF (2017) Global Nutrition Monitoring Framework: Operational Guidance (.pdf)