Primary and Secondary Outcome Measures for the Working on Rapid Language Development Trial

 Receptive and expressive languagePreschool Language Scale, Fourth Edition12Expressive score: Expressive Communication subscale; Receptive score: Auditory Comprehension subscale; both yield a standard score of 100 (SD 15)
 Caregiver use of strategiesObservational coding of a 20-min play-based caregiver-child interactionMatched turns: percentage of adult utterances in response to a child’s utterance; Responsiveness: percentage of child utterances to which the adult responded; Targets: percentage of adult utterances that contained the child’s language target; Expansions: percentage of child utterances to which the adult imitates and adds a word; Time Delays: percentage of nonverbal prompting sequences that were used correctly; Prompting: percentage of verbal prompting sequences that were used correctly
 Caregiver stressParenting Stress Index, Fourth Edition15Total Stress score
 Receptive vocabularyPeabody Picture Vocabulary Test, Fourth Edition16Standard score with a normative mean of 100 (SD 15)
 Expressive vocabularyMacArthur-Bates Communicative Development Inventories: Words and Sentences14Total number of 680 words the caregiver reports that the child says
Number of Different Word RootsTotal number of different word roots the child says in a 20-min play interaction with a research assistant
Expressive One-Word Picture Vocabulary Test, Third Edition13Standard score with a normative mean of 100 (SD 15)
 Presence of language delayPreschool Language Scale, Fourth Edition12Total standard score <85