2. Method
2.1. Design
The current study employed a secondary analysis of longitudinal data from a government-sponsored evaluation of SEND provision in schools in England (Humphrey et al., 2011). Data were analysed in two steps: first by establishing significant risk factors for behavior difficulties longitudinally within this population (Oldfield [3_TD$DIFF], [9_TD$DIFF]2012); and second by summing these risk factors to form a cumulative score to assess the cumulative risk hypothesis.