A study by academics at the London School of Economics has questioned the value for money provided by education inspectorate Ofsted.
The LSE academics, who will publish a book on watchdog bodies in April, say that it is impossible to tell whether Ofsted and other watchdogs are cost effective in terms of improvements achieved measured against money spent.
Christopher Hood, one of the LSE co-authors of the book Regulation Inside Government: Waste Watchers, Quality Police and Sleaze Busters, is due to give evidence next Wednesday to the Commons' education sub-committee investigating Ofsted.