UK-CDI Information for researchers and practitioners

Accurate, reliable language norms are critical for research on language development, for clinical practice and for policy making. For example, it is impossible to assess the impact of severe socio-economic disadvantage on language development without accurate descriptions of how much language, and of what type, we would normally expect UK children to produce and comprehend. Nor can early years and speech language specialists determine if a child is in need of extra support around their language without knowing what a typical child should be doing at a certain age.

Since most language milestones occur in the first years of life, language norms for very young children are particularly important. However, they are also difficult to obtain because most language tests cannot be easily used with very young children. An effective solution is to use parent-completed Communicative Development Inventories (CDIs), in which parents fill in a wide-ranging checklist of their child’s communicative behaviours. CDIs and CDI language norms are used extensively in many countries in virtually every area of child language and child development research. We are the first research group to create standardised CDIs and CDI language norms for UK English. Until now, the lack of these norms has had a substantial negative effect on UK research in child development, restricting the types of questions that research can answer and the scale of UK studies.

Previous CDIs were sometimes used by UK researchers but many had no norms at all or were normed in the US and this can lead to misinterpretation of the language level of British children (see Hamilton et al., 2000 for evidence that applying US norms to UK children will over-estimate the number of children with language delay in the UK).

The aim of our completed project was to create the first standardised UK CDI - the UK CDI (Words & Gestures) - and to use the measure to establish population norms for UK children aged 8 to 18 months.
The test and norms by age will in future be published as a commercial standardised test. In addition, data on a word-by-word basis will be made freely available worldwide via web-based UK Child Language Database. We will then use the data to publish two large-scale investigations. The first will assess the role of socio-economic factors in predicting language development in the UK; in particular, which factors put children most at risk for language delay and which factors may provide a level of protection. The second will establish whether vocabulary size and composition differs substantially across children learning different languages or learning different dialects of English, to inform cross-linguistic comparisons.

Our team have Level 1 authorisation granted by the CDI governing board, which gives us exclusive rights to publish a UK version. The project will have a substantial positive impact on UK research, particularly our ability to contribute to international debates about early language and cognitive development.

Currently (2017) preliminary norms and versions of the UK-CDI (Words & Gestures) and our demographic questionnaire, the Family Questionnaire, are available for download from this website. You are free to download and use these until expiry (April 2018). By downloading them and using them you accept our Terms and Conditions.