The assertion that calculators hold back pupils' performance in maths could be a myth, according to a detailed investigation which turns existing policy on its head.
A review of results from the Third International Mathematics and Science Study (TIMSS), in which Scottish and English pupils were outshone by counterparts in Europe and the Pacific Rim, concludes: "The statistics do not suggest that sensible calculator usage can be blamed for any shortcomings in students' achievement."
The study, by Ann Kitchen of Manchester University education department, warns that the drive to ban calculators in English primary schools and limit their use in Scotland "seems to be fuelled solely by the misapplication of the TIMSS results".
John Searl of Edinburgh University's centre for mathematical education said Ms Kitchen's work called into question the assumption by HMI in its report on 5-14 maths that the use of calculators needs to be reined in.
Her most startling discovery is that 13-year-olds using calculators nearly every day performed best in 16 out of 35 countries.
"Two-thirds of the countries where there was variation in calculator use found that students with the highest mean score used calculators more frequently than those with the lowest mean score," Ms Kitchen reports in the Journal of the Association for Teachers of Mathematics.
Among the nine-year-olds taking part in the TIMSS study, "well over half the countries found that their cohorts who used calculators performed best". Ms Kitchen concludes that "there is no justification for banning the sensible use of calculators".
She points to other dangers in international comparisons, particularly the way different countries organise schooling for older pupils and the differing ages of the pupils compared (largely 12 to 13-year-olds in Scotland, for instance, but mainly 13 to 14-year-olds in Japan).
Leader, page 14