McConnell (2018) Empirical studies on early intervention services for toddlers aged 24–36 months: A systematic review

This systematic review aimed to examine empirical evidence relating to the level and developmental appropriateness of service provision for two-year-olds. To be included in this review, studies had to have been published before 2006, had to have an explicit focus on service provision for two-year-olds and had to have a randomly assigned control group. Following the application of the inclusion/exclusion criteria,11 studies were included in the review. The relatively small number of eligible studies and findings suggesting a limited impact from a number of the studies suggests there is a lack of empirical evidence available. Therefore, determinations with regards to what constitutes as developmentally appropriate and effective practice for this age group could not be made.