Word usage as measured by parental checklists and language samples: trends, comparisons, and implications.

Background: Although parental checklists are well-known for their potential in indexing young children's lexicon size, they can also be used to track children's acquisition of individual words. Word-level data can be used to identify the checklist words most and least commonly employed across groups of children. Like parent-completed vocabulary checklists, samples of spontaneous language use collected from multiple children can also generate measures of word commonality, concerned with the numbers of children producing individual words.