The approach now used in the CASC exam uses a global A (clear pass) to D (clear fail) rating to determine the overall standard for the station. Examiners are asked to grade the candidate from the following scores :
A: Clear Pass
B: Borderline Pass
C: Borderline Fail
D: Clear Fail
Example marking sheets are available for download as PDF documents below:
In addition, the examiners are able to highlight "areas of concern" which do not appear to govern the overall pass/ fail decision, but may be helpful for feedback to unsuccessful candidates. The areas of concern in the Autumn 2008 CASC include:
It would not appear that such 'areas of concern' are involved in determining the grade for the station, and it doesn't seem as though any weighting is applied. For example, it is possible to have 2-3 areas of concern ticked but still pass the station, and one may potentially fail a station without having areas of concern highlighted.
In this sense, the CASC is no longer 'objective' - not that it ever was. You appear to be judged on overall performance in the station. However, and this is unclear, examiners may be directed to consider the areas of concern when deciding on the grading for the station.
It is not entirely clear how the overall pass mark for the exam is being determined. However, a simple 'Clear Fail' on a station is probably being used on an individual basis. Compared to more balanced ways of scoring OSCE exams (see below), the likelihood of a pass on a station is not governed by performance of the entire group.
Since candidates will be taking the CASC after 30-48 months of training, the standard is that expected of an ST2-3. In this sense, the 'age' of the candidate is one to two years later than the current Part I OSCE exam and higher standards will be expected. The constructs of each OSCE are likely to test more complex reasoning and management skills and may combine a variety of skills in a single OSCE.
For more information on how OSCE exams are traditionally score (but not the CASC), please see the trickcyclists OSCE format information.