the lack of confounding variables.
Many of the children studied in orphanages had experienced varying degrees of trauma.
However, the children from Romanian orphanages had in the main been handed over by loving parents that could not afford to keep them. This means that the results are much less likely to be confounded by other negative early experiences.
however, studying children from Romanian orphanages might have introduced different confounding variables, the quality of care was remarkably poor with children receiving very little intellectual stimulation or comfort