This analysis shows growth curves for vocabulary size, the number of words that a child produces or understands, for different languages, forms, and measures. For some datasets, it is possible to compare growth curves across different demographic groups (birth order, ethnicity, gender, mother's education). Use a median quantile type to compare demographic groups on a single plot, or other quantile sizes to see separate curves and plots for each groups. See below for more details and an important disclaimer about clinical usage.


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Plot description. This vocabulary norms plot shows all administrations of a particular CDI instrument within the instrument's valid age range. Dots show individual children, with age binned in whole months (and jittered to avoid overplotting). Lines on the plot indicate estimates of percentiles, fit using quantile regression with monotonic polynomial splines as the base function (Muggeo et al., 2013; gcrq function from the quantregGrowth package in R).

Disclaimer. Wordbank visualizations reflect the available data, dynamically combined from different sources that may not be identical to those included in the norming samples for a particular instrument. In particular, users should be aware that the values provided by Wordbank for English and Spanish are based on different participants and are estimated following different computational procedures than the values published in the User’s Guide and Technical Manual (Fenson et al., 2007; Jackson-Maldonado et al., 2003) and applied in the CDI Scoring program (Marchman, 2013).

In general, we do not recommend that Wordbank-generated norming values be used for research or clinical purposes in which the goal is to evaluate children's performance in reference to an established normative standard (e.g., determining the mean words produced percentile of a group of children in a study; classifying whether the performance of an individual child falls below the 10th percentile). For these types of applications in English and Spanish, users should refer to the norms and guidelines published in the manuals for those languages (available from Brookes Publishing Co). For similar applications in other languages, users should refer to the appropriate manuals and norming information, as listed on the contributors page.