Too good to be true

Dramatic effects

Expect interventions to have moderate, small or trivial effects, rather than dramatic effects.

Few interventions have effects that are so large that fair comparisons (designed to reduce the effects of biases and the play of chance) are not needed.

BEWARE of claims that suggest that an intervention has worked on all or most students or that it has led to dramatic results (either positive or negative).

REMEMBER Dramatic effects of interventions are very rare in education.