Randomised controlled trials for policy interventions: a review of reviews and meta-regression.
Oliver
S
S
Social Science Research Unit, Institute of Education, University of London, UK.
Bagnall
A M
AM
Thomas
J
J
Shepherd
J
J
Sowden
A
A
White
I
I
Dinnes
J
J
Rees
R
R
Colquitt
J
J
Oliver
K
K
Garrett
Z
Z