NIH Baby Toolbox® methodology and norms development.

The NIH Baby Toolbox is a comprehensive battery of cognitive, motor, and social-emotional assessments designed for infants aged 1-42 months. Although many standardized, normed early developmental assessments exist, these measures are time-intensive, costly, and require trained experts to administer, score, and interpret. The Baby Toolbox is intended to serve as a "common currency" across developmental fields and provide an extension to the NIH Toolbox for Assessment of Neurological and Behavioral Function® (NIHTB), which is appropriate for individuals from 3 to 90 years of age. The Baby Toolbox was normed using a nationally representative sample of infants and toddlers aged 16 days to 48 months old from the US population (N = 2515; n = 2042 English, n = 473 Spanish). The sample was weighted to match the US Census based on the demographic targets used to create the norming plan. After data collection, the demographic targets were updated to reflect the current figures. Cases were individually weighted to ensure representativeness. Unweighted and weighted demographics are reported herein. Scores were regressed on age in months (for ages where the tests or composites were appropriate) using generalized additive models for location, scale, and shape to obtain expected reference values and standard deviations across age. The Baby Toolbox norming study has been designed to minimize bias and maximize representativeness and precision of estimates. The availability of a "toolbox" of tests built using modern measurement theory to address developmental concerns will be an important foundation for addressing critical research questions in infant neurological and behavioral health.