He added that AS-levels alone correctly predicted the outcome slightly less frequently in 68.4% of cases.
Ian, 17, is preparing for his AS-levels, and his top tip is to "do lots of exam questions".
The letter also argues that AS-levels play a vital role in encouraging "less confident students" to continue with their studies.
The government has argued that A-levels and AS-levels in their current form do not help students develop a deeper understanding of their subjects.
Many universities base their offers of places to students on the results of AS-levels which are taken in the first year of sixth form study.
Deciding which subjects to study at A-level after their first year of AS-levels allowed them to make "right choices for their future", he said.
BBC: NEWS | UK | Education | Private schools top the A-level tables
He says that a pupil taking five AS-levels will usually have to take 15 papers in the third term of the lower sixth year.
And this student, if taking three full A-levels, will take another 18 papers in June of the upper sixth year, plus any re-takes from AS-levels.
Last week, head teachers wrote to the education secretary warning that any attempt to show an overall, national result for AS-levels would present a false picture.
Mr Robinson is also concerned at how AS-levels are scheduled - saying that sitting exams in early May means that the course is compressed into two terms.
Ofqual, which has been carrying out a public consultation on changes to A and AS-levels, is expected to publish the findings of its public consultation later this autumn.
The letter says that under Labour AS-levels would continue to be building blocks towards A-levels and students would continue to choose which AS-level subjects they take as full A-levels.
There are public consultations about reforming A and AS-levels.
Brian Lightman, of the Association of School and College Leaders (ASCL), whose annual conference opens on Friday, suggested that some schools might decide simply to do three A-levels and ignore AS-levels altogether.
Mr Lightman welcomed this suggestion - as having the same course content would mean that A-levels and AS-levels in the same subject could be taught in the same class, boosting the uptake of AS-levels.
The English Baccalaureate was introduced as a measure of school performance, appearing in league tables, and showing the proportion of pupils achieving GCSEs grade C and above and some AS-levels in specified key subjects.
This is because students who have taken AS-levels can choose not to "cash in" these exams - which in effect allows them to nullify their participation and to exclude their results from any overview.
Decoupling the two sets of exams would reduce the importance of AS-levels and the plans have drawn criticism from many teachers and universities, including Cambridge, which argues that they will "jeopardise over a decade's progress towards fairer access".
Most A2 students will already have done their AS-levels last year - so will have had a good indication of whether it was worth continuing with a subject, or wiser to drop it and settle for the AS qualification.
"The results of the research encourage me to believe that the use of an SAT-type test could complement achievement tests such as A-levels and could broaden intake to British universities without lowering standards, " he said.
The missions are superbly varied - as are the levels - with action-packed sequences that could have emerged straight from a Hollywood blockbuster.
The new Welsh Bac involves a core of subjects such as communication and numeracy skills and European awareness, with optional subjects from courses already on offer such as A-levels and GNVQs.
BBC: NEWS | UK | Education | Pros and cons of replacing A-levels
The exams - mostly modular tests for AS and A-levels - will be taken in Wales, England, and Northern Ireland from Monday.
If governments continue to allow anything like "business-as-usual" levels of global warming emissions, the build-up in the atmosphere is predicted to cause a further warming of 1 to 3.5 C (1.8 to 6.3 F) over the next century, according to WWF.
Students also use the results to decide which subjects to take as full A-levels.
Owned and controlled by the member central banks, the BIS provides them with data on capital flows and sets recommended regulatory standards such as capital-adequacy levels.
As part of its "long-term greedy" mantra, Goldman forged ties at the highest levels as ex-chairman Paulson made dozens of visits to the country.
However, certain countries - such as Spain - have youth unemployment levels of more than 40%.
Become sodium-aware in restaurants as well -- understand the levels in soy sauces, ham, and cheeses.
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