Holding schools to account for performance could only be justified by the value teachers added to pupils. Each pupil had a different starting point.
Professor Tymms, who oversees the Performance Indicators in Primary Schools (PIPS) initiative which is used in a third of Scottish authorities, said schools should only be compared "like with like".
But he cautioned educational leaders from as far apart as China and Chile to avoid the English experience of paying teachers extra based on pupil performance.
"This is a very unhealthy way forward. The teachers teach their pupils, test them and then they get paid by results. We should not have such a system. It creates bad data apart from anything else," he told the British Council-sponsored conference, which focused on the Scottish approach to monitoring performance, including the acclaimed self-evaluation model.
Professor Tymms said the English accountability system was the most complex in the world with tests at ages seven, 11 and 14, backed by league tables of performance. The system of inspection by the Office for Standards in Education (Ofsted) was "harsh" and involved "naming and shaming" the poorest performing schools, frightening them into improvement.
He also believed the narrow focus on cognitive abilities was imbalancing the curriculum. Pupils' attitudes to learning, social relation-ships and physical abilities were equally important and largely ignored in monitoring.
"In the western world we are very remiss at not looking at the physical development of young children. It's so important for their long-term health but also for their affective development. We have in the West more depression among young children than ever before and yet if you are feeling a bit depressed the best way to change it - unless it's clinical depression - is vigorous physical activity. Clinical trials show this to be the case but we are depriving young children of that kind of thing in many schools," Professor Tymms said.
Schools in the West were "mad" to teach foreign languages mostly after the age of 11 when language capacities were already less acute.