Table 2 Background measures
Measure | Time | Description |
|---|---|---|
Parent SES | Time 1 | A parent questionnaire determined the highest education qualification (averaged across parents if applicable), as a proxy for socio-economic status (1 = high school, 3 = post-graduate studies). |
Autism symptom severity | Time 1 | The experimenter completed the Childhood Autism Rating Scale (CARS) [44]; higher scores indicate greater autism symptoms. |
Non-verbal cognition | Time 2 | Visual reception and fine motor subtests of Mullen Scales of Early Learning [45] were transformed into a developmental quotient (developmental age/chronological age) |
Receptive language | Visit 1 | Number of words understood according to the British Communicative Development Inventory [46], completed by parents. |
Expressive language | Visit 1 | Number of words spoken according to the British Communicative Development Inventory [46], completed by parents. |
AAC use | Visit 1 | A parent questionnaire determined whether the child regularly requests 10 or more items using any augmentative alternative communication system (coded as yes/no). |
Total therapy | Visit 2 | A parent questionnaire was used to describe and quantify all therapies undertaken by the child in the previous 4 months (h/week). |
Speech and language therapy | Visit 2 | A parent questionnaire was used to describe and quantify all speech and language therapy undertaken by the child in the previous 4 months (h/week). |