“…However, in all studies that included a training component and reported positive outcomes for children (see sections above) training was intensive and did not occur as an isolated training event. At Tier 1, successful professional development for education staff was at least 8 hours (in the Starling et al, 2012 study), but more often closer to 50-60 hours in Snow et al (2014) and studies in the meta-analysis by Markussen-Brown et al (2017) and accompanied by individual coaching or observation sessions. Tier 2 studies involved relatively intensive initial training (four days in Fricke et al, 2013;Bowyer-Crane et al, 2008) followed by regular (fortnightly), on-going training, support and monitoring for staff delivering programmes.…”