The most comprehensive study yet of teacher appraisal has underlined the dangers of any link to performance-related pay, its authors say.
Despite recent calls by Chris Woodhead, the chief inspector, for the two to be brought closer together, their findings suggest such a move would seriously undermine the appraisal system.
The two-year study, led by Professor Ted Wragg of Exeter University and funded by the Leverhulme Trust, was based on a survey of more than 1,100 teachers and appraisers. The researchers also asked all 109 education authorities about training provided for appraisers, and carried out 29 studies at primary and secondary schools.
The findings, published yesterday, reveal the commitment and resources given to appraisal by LEAs and schools varies tremendously.
While 70 per cent of teachers felt they had derived some benefit from their appraisal, only 50 per cent said the review had made a difference to their teaching methods - a "disappointing" success rate, according to Professor Wragg.
Many teachers felt their appraiser was inadequately trained. Nearly 30 per cent were observed only once, instead of twice as Government guidelines require.
The overwhelming majority of teachers saw the process as a means of professional development, and opposed linking appraisal with pay and pro-motion.
"What came out in the findings is that people are most likely to change when there are good relationships and respect between appraiser and teacher, " Professor Wragg said.
"The difference between an inspection by the Office for Standards in Education, which is terribly fraught, and an appraisal, which is collegiate, is enormous."
With three-fifths of teachers aged over 40, successful appraisals addressed deep-seated teaching habits, he added.
"It is not based on hit squads and intimidation: it is based on trust and support and respect. The fact that someone comes in and says 'Here's a few quid extra' is not going to make you change."
Last month's OFSTED report supporting wider use of performance-related pay showed "an astonishing coincidence between OFSTED conclusions and Government preferences," Professor Wragg said.
The report, Teachers' Appraisal Observed, recommends that some LEAs need to provide better training and support for appraisers, especially for classroom observation. Greater use of peer appraisal should also be explored.
More time and money is needed, not just for appraisals themselves, but for follow-up meetings, and to meet identified training and professional development needs.
Teachers' Appraisal Observed, by EC Wragg et al, published by Routledge at Pounds 12.99 and Pounds 40.