NATIONAL testing is an expensive business, costing more than pound;30 million every year.
The tests are taken by 1.8 million seven, 11 and 14-year-olds in around 24,000 schools each summer and ensuring that standards are maintained is a time-consuming and complex task.
The Government's curriculum quango, the Qualifications and Curriculum Authority, is responsible for administering the tests, but contracts out key stage 2 English test development to Britain's largest educational research centre, the National Foundation for Educational Research.
Each test takes around two years to develop and involves more than 100 teachers, literacy consultants and academics as well as QCA and NFER officers.
Each test is pre-tested at least twice to give a measure of how children respond to the questions in a "real" exam situation.
Two alternative tests are developed to provide a "spare" if the first is compromised by a security leak.
When around 2,000 children sat the first pre-test in November 1997, each test had two alternative question booklets, with 500 pupils sitting each test.
A statistical analysis of how many children successfully answered each question was used to assemble one question booklet for each test, constructed so that the average child would score approximately 50 per cent.
The second pre-test was taken in April 1998 by 2,000 11-year-olds who took the proposed 1999 test three weeks before their actual 1998 test. Statisticians then analysed their results to compare performance in the 1998 and proposed 1999 tests.
Meanwhile, panels of experienced teachers set thresholds for each performance level by judging how difficult a borderline pupil would find each question.
An initial level-setting meeting in February this year considered their recommended thresholds and other statistical evidence to produce a pass mark. It was this meeting that recommended the controversial cut in the pass mark from 51 to 47 per cent this year which prompted the inquiry.
However, after the real test was taken on May 12 a final script analysis in June raised the pass mark to 48. A script scrutiny by chief markers had judged that children found the test easier than expected, and a check of 30,000 test papers confirmed this.