Within the culture as a whole, natural science has been so successful that the word scientific is used in ( manner; it is often assumed that to call something "scientific" is to imply that its reliability has been ( by research whose results cannot reasonably be (

Chen's research team randomly assigned some newborns and their mothers either to a breastfeeding promotion group (where breastfeeding was encouraged, but not required) or to a normal pediatric care group (where breastfeeding was neither encouraged nor discouraged). which research method did they use?