This is done through the work of the judges during the marking process.
There are a group of markers appointed to align the raw marks each year.
What they do is consider the difficulty of the questions, the marking guidelines and the Performance Descriptor Bands and then work out what they think the minimum mark at each band should be for each question (or a the most common question within the different sections of the paper due to the number of questions e.g. WWI usually do the Core, one Germany essay, Speer and one essay from the final section).
As the Band 1 section takes the marks from 0 - 49 the marks need to be aligned from 0 - 100 to really being 50 - 100.
As a result it is possible for the lower levels to scale up markedly considering that the raw marks are given over the full range of marks but achieving the lowest minimum standard is set at 50.
Having been a judge for a couple of years I found it interesting to see how it is down but do think students should get their raw marks. What has the BOS got to hide? Telling students they got 50 or higher when their raw mark was below 30 or even below 20 is dishonest IMHO but ....
