We are grateful to the CDI Advisory Board for permission to adapt the MacArthur-Bates Communicative Inventories to Norwegian. We thank Master of linguistics Kristin Wium for drafting the first version of the Norwegian CDI, PhD (linguistics) Janne von Koss Torkildsen, Lars Smith, and Stephen von Tetzchner, professors of psychology at the University of Oslo, for evaluating the first draft, and Masters of linguistics Eli Anne Eiesland and Laila Yvonne Henriksen for serving as COMMUNICATIVE SKILLS IN NORWEGIAN CHILDREN 2 research assistants on the norming study. We also thank the Journal Editors and two anonymous reviewers for helpful comments to this manuscript. Finally, we would like to thank the parents of the participating children for having completed the CDIreports.

Parent report has proven a valid and cost-effective means of evaluating early child language. Norming datasets for these instruments, which provide the basis for standardized comparisons of individual children to a population, can also be used to derive norms for the acquisition of individual words in production and comprehension and also early gestures and symbolic actions. These lexical norms have a wide range of uses in basic research, assessment and intervention. In addition, cross-linguistic comparisons of lexical development are greatly facilitated by the availability of norms from diverse languages. This report describes the development of CLEX, a new web-based cross-linguistic database for lexical data from adaptations of the MacArthur-Bates Communicative Development Inventories. CLEX provides tools for a range of analyses within and across languages. It is designed to incorporate additional language datasets easily, and to permit users to define mappings between lexical items in pairs of languages for more specific cross-linguistic comparisons.

The SI-3 captures a variety of language skills and is good at differentiating children in the lower end of the tail; it is thereby suitable for population language screening, although results indicated the need for some revision.

Several research groups have previously constructed short forms of the MacArthur-Bates Communicative Development Inventories (CDI) for different languages. We consider the specific aim of constructing such a short form to be used for language screening in a specific age group. We present a novel strategy for the construction, which is applicable if results from a population-based study using the CDI long form are available for this age group. The basic approach is to select items in a manner implying a left-skewed distribution of the summary score and hence a reliable discrimination among children in the lower end of the distribution despite the measurement error of the instrument. We report on the application of the strategy in constructing a Danish CDI short form and present some results illustrating the validity of the short form. Finally we discuss the choice of the most appropriate age for language screening based on a vocabulary score.