Evaluating Programme Impact: Levels of Certainty

The number and variety of early intervention models and programmes for at-risk and handicapped infants and their families has increased dramatically in the last two decades. This increase can undoubtedly be attributed to the intrinsic appeal of early intervention which draws on concepts of stimulation and prevention from developmental psychology and medicine. The intrinsic nature of this appeal is grounded in the belief that early development is more plastic than later development and that intervention in this sensitive period is thus likely to have greater preventive or ameliorative effects than in other periods. This belief underlies most early intervention programmes and currently finds its expression in an array of programmes for handicapped and at-risk infants in hospitals, homes and child care facilities.