In fact, the only evidence of success of retention is when it is done
because of the lack of immaturity of the learner and that should be a
joint decision of parents and teachers and pupils.
Studies also show the retention is much more widely used with minorities
and poor children from poor families.
An inflexible policy of retention compounds itself. Children who repeat
one grade are very likely to repeat a second or third time during their
careers.
Ironically, the Rice study focussed on the financial costs to schools of
keeping kids a grade more than a year.
One more issue: in countries where school attendance is not compulsory
or attendance is not well enforced, the children who do not succeed
disappear from the schools. In Mexico for example schools routinely plan
two second grade classes for every three first grade classes. The norm
if that a third of the children will not pass to second grade.
Ken Goodman