Table 5.
Summary of demographic and school-age candidate predictor variables included in the analysis.
| Grouped variable | Specific variable | Method of data collection | Timing of data collection a |
|---|---|---|---|
| Demographic | Gender (categorical: boy/girl) | Birth records from midwife | Birth |
| Ethnicity (categorical: White/non-White) | Questionnaire to mother | 32 weeks gestation | |
| Level of maternal education b (categorical: < O level/O level/> O level) | Questionnaire to mother | 32 weeks gestation | |
| Maternal occupation (categorical: nonmanual/manual) | Questionnaire to mother (supplemented with information on father if information on maternal occupation was not available) | 32 weeks gestation | |
| Home ownership (categorical: mortgaged or owned/rented or other) | Questionnaire to mother | 8 weeks gestation | |
| Maternal age at birth of child (continuous) | Midwife records | Recruitment to study | |
| Later speech and language performance | Language comprehension (continuous) | Listening Comprehension subtest of Wechsler Objective Language Dimensions Part II | Focus at 8 |
| Diadochokinetic tasks (a measure of oral motor skill; categorical: correct/incorrect) | Repetition of a variety of syllables (pe, te, ke, peteke, bedege) for 10 s each (Northstone et al., 2006) | Focus at 8 | |
| Phoneme deletion (continuous) | Auditory Analysis Test (Rosner & Simon, 1971) | Focus at 7 | |
| Difficulty pronouncing sounds (categorical: yes/no) | Questionnaire to mother | Child aged 81 months | |
| Nonword repetition (continuous) | CNRep (adapted; 12 items: four each of three, four, and five syllables; Gathercole & Baddeley, 1994) | Focus at 8 | |
| Literacy and learning performance | Reading test (continuous) | WORD Reading subtest (Rust et al., 1993) | Focus at 7 |
| Spelling test (continuous) | SpellingTest (15 words; Northstone et al., 2005) | Focus at 7 | |
| School assessment: reading (categorical: achieved expected level/underachieved/exceeded expected level) | Key Stage 1 Standard Attainment Tests | End of year 2 in U.K. primary school (child aged 6–7 years) | |
| School assessment: writing (categorical: achieved expected level/underachieved/exceeded expected level) | Key Stage 1 Standard Attainment Tests | End of year 2 in U.K. primary school (child aged 6–7 years) | |
| Identified learning problem (categorical: yes/no) | Questionnaire to mother | Child aged 77 months | |
| Other developmental variables | Verbal IQ (continuous) | WISC-III UK (reduced form using alternate test items) | Focus at 8 |
| Performance IQ (continuous) | WISC-III UK (reduced form using alternate test items) | Focus at 8 | |
| Combined IQ score (continuous) | WISC-III UK (reduced form using alternate test items) | Focus at 8 | |
| Auditory memory (continuous) | Digit Span subtest of WISC-III UK (reduced form using alternate test items) | Focus at 8 | |
| Spatial ability (continuous) | Block Design subtest of WISC-III UK (reduced form using alternate test items) | Focus at 8 | |
| Attention (continuous) | Sky Search task from TEACh (Manly et al., 1998) | Focus at 8 | |
| Friendships (continuous) | Friendships questionnaire (Goodyer et al., 1989, 1990) | Focus at 8 | |
| Suspected coordination problem (categorical: yes/no) | Questionnaire to mother | Child aged 103 months | |
| Tympanostomy tubes fitted at any time (categorical: yes/no) | Questionnaires to mother and hearing assessment | Child aged 69 months and 81 months (questionnaires); Focus at 7 (hearing assessment) | |
| Hearing impairment (categorical: yes/no) | Pure-tone audiometry | Focus at 7 |
Note. Comments in parentheses indicate whether the variable is categorical (with specified categories) or continuous. CNRep = Children's Test of Non-Word Repetition; WORD = Wechsler Objective Reading Dimensions; WISC-III UK = Wechsler Intelligence Scale for Children–Third UK Edition (Wechsler, Golombok, & Rust, 1992); TEACh = Test of Everyday Attention for Children.
“Focus” is the name of the assessment clinics that children from the Avon Longitudinal Study of Parents and Children sample were invited to attend. “Focus at 8” is the name of the clinic that children attended at age 8 years; “Focus at 7” is the name of the clinic that children attended at age 7 years.
“O level” was the qualification obtained at age 16 years when the parents of the cohort were at school.