Description of variables explored in the analysis
| Level | Variable | Source |
| Individual | Preschool mental health difficulties | Teacher-rated SDQ—Education Services routine data |
| Sex | Education Services routine data | |
| Ethnicity | Education Services routine data | |
| Glasgow Index of Multiple Deprivation (at preschool and Primary 3) | From child’s home postcode, which is collected as part of Education Services routine data | |
| Looked After Status (at preschool and Primary 3) | Education Services routine data | |
| School | Religious affiliation (denominational or non-denominational) | Education Scotland |
| Her Majesty’s Inspectorate for education (HMIe)/Education Scotland follow-up report required (where the initial school report was unsatisfactory) | Education Scotland | |
| School pupil roll | Schools census—Education Services routine data | |
| School exclusions per 1000 pupils | Schools census—Education Services routine data | |
| Proportion of children entitled to free school meals (a means-tested benefit when collected) | Schools census—Education Services routine data |
SDQ, Strengths and Difficulties Questionnaire.