Measurement of expressive vocabulary in school-age children: Development and application of the Kilifi Naming Test (KNT)

ABSTRACT

The dearth of locally developed measures of language makes it difficult to detect language and communication problems among school-age children in sub-Saharan African settings. We sought to describe variability in vocabulary acquisition as an important element of global cognitive functioning. Our primary aims were to establish the psychometric properties of an expressive vocabulary measure, examine sources of variability, and investigate the measure’s associations with non-verbal reasoning and educational achievement. The study included 308 boys and girls living in a predominantly rural district in Kenya. The developed measure, the Kilifi Naming Test (KNT), had excellent reliability and acceptable convergent validity. However, concurrent validity was not adequately demonstrated. In the final regression model, significant effects of schooling and area of residence were recorded. Contextual factors should be taken into account in the interpretation of test scores. There is need for future studies to explore the concurrent validity of the KNT further.

KEYWORDS:

• Contextual factors
• expressive vocabulary
• Kilifi Naming Test
• reliability
• resource-limited settings
• school-age children

Acknowledgments

This paper is published with the permission of the Director of KEMRI. The authors would like to thank L. Mbonani, J. Gona, R. Kalu, H. Garrashi, R. Mapenzi, and C. Mapenzi for their role in data collection; and K. Katana and P. Kadii for data entry. Our sincere gratitude goes to the children and their families who participated in this study and who generously gave their time to make this work possible. We are also grateful to the head teachers of the schools which were involved in the study for permission to recruit pupils from their schools.

The authors gratefully acknowledge the contribution of the late Prof. Kevin J. Connolly (deceased December 2015) who provided insight and expertise that informed the conceptualization of the main study through which the data for the current study were collected.

Additional information

Funding

The study received administrative and financial support through the KEMRI-Wellcome Trust Research Program. Penny Holding was supported by a Wellcome Trust Advanced Training Scholarship (grant number OXTREC 024-02).