Background Information:
Countries have long required measures that are valid and reliable to monitor development among children from birth to 36 months but standardized and globally applicable population-based measures have been scarce.
Existing measures were either designed to monitor the development of children after 24 months or lacked sufficient consideration for the diversity of contexts in which children are raised. Other measures required extensive resources to be implemented.
The new methodology (Global Scales for Early Development (GSED)) was developed based on a common dataset collected from 51 cohorts in 32 countries, of which 30 are low- or middle-income countries, by a multi-disciplinary team of global experts coordinated by WHO.
To date, the GSED measures have been validated in Bangladesh, Pakistan, and United Republic of Tanzania (1248 children per country) and data collection is ongoing in Brazil, China, Côte d’Ivoire and the Netherlands.
The current package comprises the measures (Short form and Long form), related user manuals and item guides, translation and adaptation guide, scoring guide and technical report summarising the methodology and the results of its validation. A GSED App is also available. The GSED will continue to evolve and an expanded version of the package, including global norms and standards for child development, will be released following additional data collection.
Key Messages:
The World Health Organization (WHO) has recently rolled out a new holistic way to measure early childhood development.
This new package of measures, the Global Scales for Early Development (GSED), helps monitor the development of young children at population level up to three years of age.
The new GSED methodology allows for a comprehensive assessment of the development of young children up to 36 months of age, capturing cognitive, socio-emotional, language and motor skills.
The GSED is delivered through open access, culturally neutral forms that are easy to use across the world, with minimal adaptation required beyond translation. They are relevant across different contexts, including in emergency situations as well as in large-scale data collection efforts.
The GSED meets the measurement objective by incorporating all domains of child development through a common scale for measurement translated into a single score, the Developmental score (D-score), that represents holistic development, and can be tracked over time.
D-Score
The D-score is a unit of measurement with an interval scale representing child development by a single number. As height (in centimetres) and weight (in
kilograms) change over time with the growth of the child, development (measured in D-score units) also increases with age as the child acquires more skills.
The D-score is calculated from Yes/No responses on a set of age-appropriate developmental items (e.g. “Can the child stack two blocks”, or “Does the child use two-word sentences?”). Conceptually, a child’s D-score falls along a developmental continuum, beginning with simple skills and behaviours that the child is able to perform
and progressing through the child’s repertoire until reaching skills and behaviours that the child has yet to acquire. It is calculated as the mean of the posterior distribution conditional on the responses, the items’ difficulty and the child’s age.
The D-score may also be transformed into the Development-for-Age z-score (DAZ). The DAZ is age-independent and is scaled such that at each age, the distribution of scores is normally distributed with a mean of 0 and a variance of 1. Since DAZ adjusts for the natural increase in D-score with age, it helps ease the comparison between samples from different ages or countries. Similar to height-for-age z-score (HAZ) and weight-for-age z-score (WAZ), the DAZ is calculated relative to a reference population.
Administering the GSED
Children are divided into 12 age bands of three months each (from 0<3 months through 33<36 months).
To start, begin with the first item in the age band that corresponds with the child’s age in months.
If the caregiver responds “No” or “Don’t know” to any of the first three items in the age band that corresponds to the child’s age, then go back to the earlier age band and proceed with the administration of those items.
If the caregiver responds “No” or “Don’t know” to any of the first three items in the earlier age band, continue going back until the caregiver answers “Yes” to all of the first three items in the selected age band.
To stop, once the starting age band has been established (i.e. the first three items have been answered as “Yes”), continue administering the Short Form. The interview should stop when the caregiver provides five “No” and/or “Don’t know” responses in a row.
Useful Links:
Link to the related WHO news release:
Link to Global Scales for Early Development v.1.0:
https://www.who.int/publications/i/item/WHO-MSD-GSED-package-v1.0-2023.1
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