UMS

TSR Wiki > Study Help > Exams and Qualifications > A Levels > UMS

A Uniform Mark Scheme, or UMS, is a way of standardising the marking of papers across different examination sessions and examination boards, allowing one to compare two marks marked by two different examination boards or the marks between different papers of the same module sat in different sessions. Grades are then calculated using grade boundaries setting certain raw marks at particular UMS scores.

In subjects such as sciences or mathematics where it is relatively easy to get a full score if you know the content very well then the UMS and raw scores are likely to correlate quite well. However, in more subjective subjects like English or languages where a full score is less likely, a lower score, of perhaps 85% of the raw mark, will be sufficient to gain a full UMS.

Legacy Specifications

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.

Post-2008 Specifications

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.

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.

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.

The Procedure

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:

1. Work out the gap between your grade's boundary and the boundary of the grade above in raw marks;
2. Work out 10% of the total UMS marks (which is the gap between your grade's upper and lower boundaries in UMS marks);
3. 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);
4. Divide the number worked out in step 3 by the number worked out in step 1;
5. 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);
6. 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:

So 32 is a C; it falls into the linear range. But what UMS score is 32/62 raw marks?

1. raw gap = B - C = 39 - 27 = 6
2. UMS gap = 10% of 100 = 10
3. how far into a C in raw marks = 32 - 27 = 5
4. 5 ÷ 6 = 0.8333...
5. how far into a C in UMS marks = (5 ÷ 6) × 10 = 8.333...
6. 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:

1. Work out the gap between your grade's boundary and the boundary of the grade above in raw marks;
2. 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);
3. Subtract your grade's UMS boundary from your UMS score (which gives you how far you are into your grade in UMS marks);
4. Multiply the number worked out in step 3 by the number worked out in step 1;
5. 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);
6. Add this to your grade's raw boundary, then round to the nearest whole number if appropriate, to give your raw mark.

It is perhaps easier to remember the relationship:

It is almost certainly easiest to just use the Excel file graciously provided by a TSR member: UMS-to-raw-v2.4.xls

Some Notes

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.