PhD grading

30 January 2010
Many taught students have asked me about the way PhD degrees and assessed and classified. Although PhD degrees are only pass/fail without any grading of the quality of the work, the process by which a pass or fail is finalised is a bit different. Basically a pass can have conditions attached, and a fail does not mean you end up with nothing.
Pass unconditionally
This is rare.
Pass with minor corrections
The most common result. Considering the number of caffeine-fuelled panics that go into writing a dissertation, a surprisingly large number of errors can slip in. Since PhD dissertations are almost always published and constitute original work, correcting errors is more important than with taught degree dissertations that tend to sink without trace after a year or so. Minor corrections typically include things like spelling, misnumbered figures, ambiguous statements, misdirected references, and errors in diagrams. As a general rule, anything that does not require significant change to the hypothesis or the conclusions of the dissertation can be classified as minor.
Major corrections required
There are problems with the dissertation content, which can include non-consideration of important factors, conclusions that do not follow from the results, incorrect results, or faults with the arguments. However the fundamentals of the PhD work are sound. This can sometimes also be used if minor errors are so cumulative that it makes the dissertation hard to follow, and correcting them would take a significant amount of time. Variations in policies mean that what might get away with major corrections at one university will require a second viva at others. For instance Heriot-Watt only allows major corrections to the satisfaction of the internal examiner, whereas Bristol requires the external to sign them off as well, and Edinburgh requires any major corrections to go to a second viva.
Re-viva required
This implies that the examiners believe that a substantial amount of work is required before a PhD can be granted, and most are usually reluctant to award anything worse than this. In many cases the dissertation was submitted against the advice of the supervisor, possibly because the writing-up was rushed by the PhD student due to external influences.
Fail, but awarded a M.Phil.
The examiners believe the work is insufficient to be awarded a PhD, and this cannot be rectified by allowing more time. However there is still a significant contribution that warrants a (lesser) M.Phil degree. This in turn can be granted unconditionally, subject to minor/major corrections, or after a further viva. In some cases an M.Phil is given as an option for people who, usually for personal reasons, do not want to do the remedial work required for a PhD.
Fail outright
Very rare, but it does happen. This implies that 3-5 years of work is irrecoverably worthless, so would bring up major questions about the conduct of the PhD. The suitability of the PhD supervisor should be called into questions in cases this bad.
Although examination boards have the final say, this in practice rubber-stamps whatever recommendation is given by the examiners at the viva. This is why many PhDs have this outwardly odd situation of having to do more work for their PhD even though they have already (unofficially) granted the degree.