Table 1.

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.