A mystery is defined as something that is difficult to understand and or explain. This describes exactly the situation we have at the moment as many examining bodies move their assessment towards scaled scoring and away from the more traditional percentage pass mark. Some argue that scaled scoring is clearer in that it allows direct comparison of one examination to another but from my experience in the short run at least clarity is not the term many would use.
The raw score
For most students the way to find out how well they are doing is to have a piece of work marked. If the total marks available are 50 and the student scores 35 then as a percentage they have obtained 70% of the available marks. This is called the raw score. Interestingly it tells you very little, for example is 70% good or bad? For a raw score to have any meaning it needs to be compared with a standard. This could be with another student or group of students, and is an example of what is called norm referencing, now this clearly has meaning as you can tell if you are performing better or worse than your peer group. But the most common way in which exam results have historically been published is as a pass/fail against a pass mark or as it is sometimes called a cut score. If the pass mark is 60% and the student has scored 70% then they have passed.
The scaled score
However raw scores are only fair if the exam sat is the same for every student. It would be unfair to give each student a different exam and set the same pass mark, unless of course you believed the exam was of an equal standard. This has been the argument in the past, yet producing an exam of equal standard is almost impossible, and this is why scaled scores are being used more often.
To use scaled scoring you need a range of marks, for our purposes let us assume the range or scale goes from 0 to 150. We then have to set a common passing score, say 100, this is the score on the scale that the student needs to achieve to pass the exam or test, and it will never change. What happens next is what makes a scaled score so useful.
A group of experts including the examiner review the exam that has just been sat, they will probably mark a number of scripts themselves and will have access to the results from all other students. Then taking into account the performance of all students and their knowledge of this particular exam they will set the pass mark for this paper. Let’s assume that the pass mark is 32, if a student is awarded a raw score of 32 on this particular paper it will be equated to a scaled score of 100. All other scores above and below 32 will also be given a scaled score equivalent.
So on some levels using a scaled score is no different to the examiner setting a different pass mark for each exam, acknowledging that the level of difficulty will never be the same for any one examination. The reason the scaling is used however is because it can be stated that the passing score for the exam is always 100, this means the standard stays the same even though the marks may change.
So there you have it, no longer a mystery….I hope?
For more information and guidance watch the video on Pearson’s web site. Click on this link and scroll down.