Exam boards try to ensure that each exam paper has the same level of difficulty from year to year, but in reality there is a little variation in how challenging a paper is for students. Hence, for modular specifications the exam boards use UMS marks to account for variations in difficulty and standardise for how everyone else performed. These marks will also contribute to your subject grade rather than the raw mark, so you won't be penalised if your exam this year is substantially more difficult than other years. :)
Each exam board has a converter which you can use to work out your UMS marks from your raw marks. If you're interested in where your marks are on the scale, you can find the links for each converter below:
Raw Mark to UMS Converters
UMS is set at 300 UMS for the AS, 600 UMS for the A2. But each of the individual units for each stage, AS or A2, are not always equally weighted. In Mathematics A-level (all specifications), every unit is weighted equally at 1/3 (33.3%) of the AS or 1/6 (16.7%) of the A-level: thus every unit is worth 100 UMS. With two-unit A-levels e.g. Edexcel Chinese, there is one unit per stage, so every unit is equally weighted at 100% of the AS, 50% of the A-level; therefore each will be worth 300 UMS.
However, there may be subjects which allocate the units unequally: OCR Critical Thinking has four units, worth 20%, 30%, 20%, 30% of a whole A-level; therefore the units are worth 120, 180, 120 and 180 UMS respectively. Units can be worth 15% (90 UMS), 16.7% or 1/6 (100 UMS), 17.5% (105 UMS), 20% (120 UMS), 30% (180 UMS), or 50% (300 UMS).
This also means that the UMS of grades, which are always the same percentages (A = 80%, B = 70%, C = 60%, D = 50%, E = 40%), will be different scores for differently weighted units.
|Grade||A-level UMS mark /600||AS-level UMS mark /300|
|Grade||Module UMS mark /90||Module UMS mark /100||Module UMS mark /105||Module UMS mark /120||Module UMS mark /180||Module UMS mark /300||Percentage UMS required|
From 2008, most subjects will move from 600 to 400 UMS for the A-level, and from 300 to 200 UMS for the AS (all the four-unit A-levels will make this shift), but those subjects staying at six units (Biology, Chemistry, Physics, Electronics, Geology, Human Biology, Science, Music, Mathematics/Further Maths/Further Maths Additional) will stay as 600 UMS for the A-level, 300 UMS for AS. The two-unit and three-unit specifications (Bengali, Modern Hebrew, Panjabi, Polish, Arabic, Japanese, Modern Greek, Biblical Hebrew, Dutch, Gujarati, Persian, Portuguese, and Turkish; Chinese will be three-unit) will all move to 200 UMS for the A-level, 100 UMS for the AS.
|Grade||6-unit A-level UMS mark /600||4-unit A-level UMS mark /400||2-unit & 3-unit A-level UMS mark /200|
|Grade||3-unit AS-level UMS mark /300||2-unit AS-level (as part of a 4-unit A-level) UMS mark /200||1-unit AS-level & 2-unit AS-level (as part of a 3-unit A-level) UMS mark /100|
There is a different range of UMS scores compared with the legacy specifications; for example, no unit now bears 300 UMS, as those that did were part of a 2-unit A-level, which now has 200 UMS.
|Grade||Module UMS mark /60||Module UMS mark /80||Module UMS mark /90||Module UMS mark /100||Module UMS mark /120||Module UMS mark /150||Percentage UMS required|
The A* started being issued for A levels from the academic year 2009-2010.
To get an A*, you must meet the following two requirements:
- 80% UMS overall (i.e. the current requirements for an A).
- 90% UMS overall in the compulsory A2 units.
- For example, in Maths A2, the compulsory A2 units are C3 and C4, so over 90% UMS is only needed in C3 and C4.
- Whereas in Physics, all the A2 units are compulsory, so 90% UMS is needed in all of them.
If you get 100% at AS but only 89% at A2 you won't qualify for an A* but even if you don't get 80% at AS as long as your overall percentage amounts to 80%+ you can get an A* with 90% at A2.
The only A-levels to be unchanged by the 2008 reform are Maths, Further Maths, Further Maths (Additional) (although some of the individual units in the Edexcel A-levels have been modified; see here), Statistics, and Use of Maths AS. No AS will have the A* grade available (so you cannot get an A* in Use of Maths).
For the Maths A-level, the A* will require an 80% of the A-level, plus 90% in the aggregate of units C3 and C4 only. This means that you must get over 180 UMS in total for C3 and C4.
For the Further Maths A-level (and presumably the Additional Further Maths A-level too), the best three A2 units will contribute to the A* grade conditions. This means that of the 6 units in Further Maths, the top 3 A2 units must have a total of over 270 UMS (i.e. an average of over 90%). A2 units for Further Maths are classed as FP2 and above, and all the 2nd applied units and above (i.e. M2, M3, M4, M5, S2, S3, S4, D2, DC, NC, DE). FP1 is classed as an AS unit and therefore wouldn't count towards the 270 UMS required for the A*.
For more information on the A* at A level please see the dedicated article for it.
Converting Raw to UMS
If you know your raw marks, the full raw marks available, and the appropriate set of grade boundaries (such as if you request your script back, or if you know your coursework mark and are estimating the future grade boundaries based on the past, or if you have written down all your answers while having the mark scheme and the grade boundaries as found on TSR itself), you can estimate your UMS. And it's the UMS that will count towards the final AS or A-level grade.
Firstly find where your raw mark lies between, and thus your grade. If your mark lies on the grade boundary, then your UMS is just the minimum UMS for the grade (see the tables above). If you got a B, C, D, or E (where the relationship is definitely 'almost linear'), then it's relatively simple to find the UMS:
- Work out the gap between your grade's boundary and the boundary of the grade above in raw marks;
- Work out 10% of the total UMS marks (which is the gap between your grade's upper and lower boundaries in UMS marks);
- Work out the gap between your raw mark and your grade's boundary below, in raw marks (which is how far you are into your grade in raw marks);
- Divide the number worked out in step 3 by the number worked out in step 1;
- Multiply this number in step 4 by the number in step 2 (which gives you how far you are into your grade in UMS marks);
- Add this to your grade's UMS boundary, then round to the nearest whole number if appropriate, to give your UMS score.
A worked example should make things clear. Let's take AQA A Psychology, PYA1, summer 2006 session, and we see that the examiners have concluded that a particular script has gained 32 overall in raw marks. From the grade boundaries:
|Scaled Boundary Mark||62||39||33||27||22||17|
|Uniform Boundary Mark||100||80||70||60||50||40|
So 32 is a C; it falls into the linear range. But what UMS score is 32/62 raw marks?
- raw gap = B - C = 33 - 27 = 6
- UMS gap = 10% of 100 = 10
- how far into a C in raw marks = 32 - 27 = 5
- 5 ÷ 6 = 0.8333...
- how far into a C in UMS marks = (5 ÷ 6) × 10 = 8.333...
- UMS score = 60 + 8.333... = 68.333...
Hence 32/62 is about 68/100.
What if I got a U, or an A?
At the bottom end of the raw-UMS conversion, the E-to-A linear relationship shifts to a different linear relationship at a point called the notional N, which is worth 30% of the full UMS. The N boundary is simple to calculate as a raw mark - just subtract the gap from D to E from the E boundary:
- N = E - (D - E) = (2 × E) - D.
If your raw score is a U, to calculate your UMS you have to determine whether you are above an N. If you are above an N but below an E, treat those two as your grade boundaries and you can follow the procedure above. If you are below an N, then use the N as your higher boundary and the U boundary (i.e. 0 raw = 0 UMS) as your lower boundary, then use the procedure above.
At the top end of the raw-UMS conversion, the distortion is even greater. The critical point here is the cap, which marks 100% UMS. To calculate this, double the interval from B to A and add that to the A boundary (the doubling is required because the A boundary is 80%, while the B-to-A gap is 10%; only when doubled does it become 20%):
- CAP = A + (2 × (A - B)) = (3 × A) - (2 × B)
If the cap is below full raw marks (as it usually is), then the raw cap mark and anything above it become 100% UMS. This is why you can lose some raw marks and still get full UMS marks. With the example for PYA1 summer 2006 above, the cap is 51/62, meaning that for that particular exam you only needed 82.2% of the raw marks to get 100/100 on your statement of results. To calculate your UMS, you can use the cap and the A boundaries in the procedure above.
If the cap is above full raw marks, then the rate of exchange above the A boundary changes. The cap then becomes full raw marks equal to full UMS marks. You can then use the modified cap and the A boundaries in the procedure.
Converting UMS to Raw
This is simply the reverse of the above procedure:
- Work out the gap between your grade's boundary and the boundary of the grade above in raw marks;
- Work out the gap between your grade's boundary and the boundary of the grade above in UMS marks (which is 10% of the total UMS marks for grades B, C, D, E);
- Subtract your grade's UMS boundary from your UMS score (which gives you how far you are into your grade in UMS marks);
- Multiply the number worked out in step 3 by the number worked out in step 1;
- Divide this number in step 4 by the number in step 2 (which gives you how far you are into your grade in raw marks);
- Add this to your grade's raw boundary, then round to the nearest whole number if appropriate, to give your raw mark.
It is almost certainly easiest to just use the Excel file graciously provided by a TSR member: UMS-to-raw-v2.4.xls
The A, B, C, D, E boundaries are usually given, but they can be worked out from the A and E grade boundaries, as the relationship between raw and UMS is always linear from the E boundary up to the A boundary. The distance between adjacent grades (A-B, B-C, C-D, D-E, a difference of 10% UMS) is a quarter of the A-E distance (40% UMS difference), so the boundaries can be calculated easily. However, the grade boundaries are always rounded down to the nearest whole number.
- B = rounddown [ ((3 × A) + E) ÷ 4 ]
- C = rounddown [ (A + E) ÷ 2 ]
- D = rounddown [ (A + (3 × E)) ÷ 4 ]
If the grade boundaries given are for a whole unit that has two or more components (e.g. OCR Biology 2803, 2806), be careful to scale components that are out of a raw mark which is not the same as its share of the UMS mark (e.g. taking 2803: Transport is out of 45 raw marks, while Experimental Skills 1 which is out of 60 raw marks; but they combine to give a 120 UMS marks with equal weighting, so both Transport and Experimental Skills 1 are out of 60 UMS, so Transport has to be multiplied by 4 and then divided by 3, whereas Experimental Skills 1 needs no scaling). This results in new component raw marks which can be added together to give the unit raw mark, which corresponds to the grade boundaries given. If the grade boundaries are already for the components, then scaling is not always necessary.
This does only give an estimate of the UMS you should receive, but it is pretty well-aligned with what AQA has said on its informative UMS leaflet.
The utmost thanks to terrafire for digging all of this information out and markdr for the UMS-to-raw converter, all available from the All About UMS thread.