OFFICIAL statistics have grossly underestimated the number of American children forced to repeat a school year, a new study suggests.

A recent US Department of Education report said that the proportion of pupils who had been put back a grade might be as low as 3 per cent. But Robert M Hauser of the University of Wisconsin-Madison claims that this estimate is indefensibly low.

“I cannot think of any rationale for this statistic, other than an effort to mislead the public about the true extent of grade retention,” he says. “It is pervasive in American schools.” Hauser estimates that at least 15 per cent of pupils aged 6 to 8 and 15 to 17 are held back, and says that the practice is widespread outside these age groups.

Relatively few white girls repeat a year but the same cannot be said of black and Hispanic boys. By the age of 15 to 17, close to 50 per cent of black boys have dropped back a year.

Hauser, who conducted the study for the Civil Rights Project at Harvard, bases his calculations on what he regards as the best available statistical evidence - long-term data collected by the US Bureau of the Census.

But his findings are unlikely to alarm the many US supporters of retention, including President Clinton, who has challenged states and school districts “to end the practice of promoting students without regard to how much they have learned”.

Last October the President sid children who were held back should be treated with “tough love”.

He said teachers should look them “dead in the eye” and say: “This doesn’t mean there’s something wrong with you, but we’ll be hurting you worse if we tell you you’re learning something when you’re not.”

His views have proved popular but retention rates vary widely across the 50 states, and across age groups. They are unusually high in the District of Columbia, but relatively low in Ohio, South Carolina and Georgia. Retention rates tend to be greater in the early primary grades - though not in kindergarten - and early high school.

The uneven pattern has developed partly because retention has produced mixed results. Some studies suggest that repeating a year can be beneficial, but, having reviewed a mass of evidence, Hauser is sceptical.

“Research data indicate that simply repeating a grade does not generally improve achievement; moreover, it increases the drop-out rate,” he concludes. “The costs of grade repetition are large - both to those retained and those who must pay for repeated schooling. Moreover, the presence of older students creates serious management problems for schools.”

Hauser argues that, rather than asking children to repeat a year, schools should be trying to identify - and remedy - learning problems at an earlier age, particularly from kindergarten through to grade 2. But he warns remedial instruction for those who fail end-of-year tests “will be neither simple nor inexpensive”.

“Should we end social promotion? Truth and consequences”, by Robert M Hauser, Center for Demography and Ecology, University of Wisconsin-Madison