Strength: fewer confounding variables than other research
there were many orphan studies before the Romanian orphans became available to study. often involved children who experienced loss or trauma before they were institutionalised
neglect, abuse and bereavement meant it was hard to observe the effects of institutionalisation in isolation. the children were affected by multiple factors functioning as confounding variables
means we can be fairly sure that differences in institutionally cared for children are the result of this type of care (high internal validity)