Introduction
The data collected in the 18 Year questionnaire study included A-level and other examination results gained at age 18. As with the GCSE results collected in the 16 Year study, collecting and entering these data involved the following issues:
- While many twins gained the common post-16 qualification types (such as A-levels and AS-levels), other twins gained rarer qualification types at age 18.
- Some of the rarer qualification types were difficult or impossible to equate to A-levels in terms of grade or workload. For example, overseas qualifications (like the IB) and a variety of vocational awards.
- In addition to qualification types that are specifically designed for post-16 study, some twins have continued to study for qualifications aimed at age 16 students.
- Twins sometimes recorded qualifications in an approximate or confusing way.
Many of these issues were anticipated to some extent, and the 18 year questionnaire was designed to collect the most common qualification types as clearly and simply as possible. Some minor improvements in the wording of the questionnaire were made between cohort 1 and cohort 2. A new section of questions about school types was added at the end of the questionnaire in cohort 3, and this was slightly further adapted for cohort 4. Hence, there are four versions of the questionnaire for cohort 1, cohort 2, cohort 3 and cohort 4 (pdfs)
The information under the headings below explains aspects of the main qualification types that are being entered, and summarises the fields used to store the raw data.
Qualification Types
The table below summarises the more common types of qualifications that have been recorded by twins at age 18. Most of the listed types (except for Scottish and overseas qualifications) are accredited by Ofqual; see the 18 Year measures page for references.
Various qualification types at age 18 that are much rarer (and hence not tabulated here), and which may or may not be accredited by Ofqual, are only recorded in an approximate way, if at all, in the data. They may, for example, be recorded as an "other overseas post-16 qualification" or an "other UK level 3 qualification", without further details of subjects or grades attained (see data entry fields below).
Note that qualifications at levels 1 and 2 (equivalent to GCSEs, and designed for age 16 students) are not entered at all in the 18 year data, even if twins occasionally recorded them in the questionnaires.
| Category | Type | Awarded By | Comments |
|---|---|---|---|
| GCE | A-level (Advanced level) | AQA, OCR, Edexcel, WJEC (Wales), CCEA (Northern Ireland), CIE (overseas) | The most common qualification type at age 16, and the traditional preparation for university entry in England and Wales. Available in the full range of academic subjects. |
| Double-award A-level | Equivalent to two A-levels. Available only for a few vocational and applied subjects. | ||
| AS-level (Advanced Subsidiary level) | Half the workload of an A-level. Typically taken during the first year of study; an AS-level may then be converted to a full A-level by taking A2-level examinations in the second year of study (the A2 does not exist as a qualification in its own right). | ||
| Vocational (level 3) | BTEC | Edexcel | A common alternative to A-levels for students following vocational courses of study. There are several different BTEC awards, with different workloads. |
| NVQ | Edexcel, City and Guilds, and many others | Highly vocational, often taken as part of an apprenticeship, or studied part-time alongside work. Equivalent in workload to 2 A-levels. | |
| Advanced and Progression Diplomas | various employers in partnership with universities | Geared to specific industry/employment sectors. They include project work and work experience components in addition to guided learning. | |
| Miscellaneous others | Extended Project Qualification (EPQ) | as for GCE A-levels above | Equivalent in workload to an AS-level. Often taken in addition to A-levels, to broaden the range of study. Student can choose their own subject matter for their projects. |
| The Welsh Baccalaureate and Scottish Highers (similar to A-levels). | Difficult to equate to A-levels. These are rare amongst
TEDS twins, and are not entered in fine detail in the data.
Students in Wales typically take the more common qualifications listed above; the Welsh Baccalaureate is a broader qualification that may incorporate these and other qualification types. |
||
| Overseas qualifications. For example, the International Baccalaureate (IB). |
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NQF Levels
UK Government guidelines set out the level at which any accredited qualification can be recognised in England, Wales and Northern Ireland. Post-16 qualifications, generally taken at age 17 or 18, are at level 3 (A-levels or exams at an equivalent level). The table below summarises the levels (up to level 4).
| Level | Equivalence in level | Common qualification types |
|---|---|---|
| Entry level | Sub-GCSE; National Curriculum levels 1, 2 and 3 | Entry Level Certificates of various types. |
| Level 1 | GCSE grades D to G |
|
| Level 2 | GCSE grades A* to C |
|
| Level 3 | GCE Advanced level (above GCSE level); A-level pass grades A* to E |
|
| Level 4 | Initial level of Higher Education (post-18); higher than GCE A-level. |
|
In the 18 year data, only level 3 qualifications have been entered. Lower levels (Entry, level 1, level 2) are entered alongside GCSE results in the 16 year study data. Higher levels (level 4 and above) are extremely rare at age 18, and are not entered.
Grades
A-level passes are graded from A* to E, while AS-levels are graded from A to E (the A* grade is not available at AS-level). Fortunately, some other common post-16 qualifications (Advanced and Progression Diplomas and EPQ) have equivalent grades A* to E. Level 3 NVQ has a simple ungraded Pass (P). Level 3 BTEC has four pass grades: Distinction* (D*), Distinction (D), Merit (M) and Pass (P).
In the TEDS data, an attempt has been made to unify the pass grades of all these qualification types using a single, ordinal, numerical code with values 1 (grade E) through to 6 (grade A*). The table below summarises the coding conventions used in the TEDS 18 year data, and the types of pass grade for each common qualification type.
| Level | Level 3 | |||||
|---|---|---|---|---|---|---|
| Grade coding | 1 | 2 | 3 | 4 | 5 | 6 |
| A-level grades (including double-award) | E | D | C | B | A | A* |
| AS-level grades | E | D | C | B | A | - |
| Advanced and Progression Diploma grades | E | D | C | B | A | A* |
| EPQ grades | E | D | C | B | A | A* |
| Level 3 BTEC grades | P | - | M | - | D | D* |
| Level 3 NVQ grade | P | - | - | - | - | - |
Workload equivalence
Different qualifications at the same level, even if they have equivalent grades, may not be equivalent in workload. For example, an AS-level is equivalent in workload to half an A-level. In the TEDS data, workload equivalences are useful for computing measurements such as mean grade or total point score across different qualification types.
Fortunately, for the main post-16 qualification types, the A-level workload equivalence is explicitly stated in the documentation. For example, a level 3 NVQ is stated to be equivalent to 2 A-levels. The table below summarises the workload equivalences that are assumed in the TEDS data for different qualification types entered at age 18.
| Qualification type | Number of A-level equivalents |
|---|---|
| A-level | 1 |
| Double-award A-level | 2 |
| AS-level | ½ |
| EPQ | ½ |
| Level 3 NVQ | 2 |
| Level 3 BTEC National Certificate | ½ |
| Level 3 BTEC Subsidiary Diploma | 1 |
| Level 3 BTEC Diploma | 2 |
| Level 3 BTEC Extended Diploma | 3 |
| Progression Diploma | 2 |
| Advanced Diploma | 3 |
Subject coding
The more common types of post-16 qualifications (A/AS-levels, NVQ, BTEC and Diplomas) all have subjects that are recorded in the data. These qualifications are offered by a range of examination boards, and many different subjects are available; new subjects may be added by the boards each year. The data entry system therefore allows new subjects to be added as and when they arise. Each subject has its own unique numeric code, and these are recorded in variable value codes in the dataset. There are separate lists of subject codes for A/AS-levels (typically academic subjects) and for NVQ/BTEC/Diploma (typically vocational subjects). The lists of subject codes for these types are quite long and are not reproduced here, as they are subject to continual change during data entry.
Subjects are not recorded for EPQ or for "other qualifications". The EPQ does not have a pre-determined subject, but takes the form of a project submitted by the student in their own choice of subject matter. The "other qualification" types may or may not have subjects, but this level of detail is not recorded in the data for these rare qualifications.
Data Entry Fields
Data from the 18 year questionnaires were entered manually using an Access database. The field names used in the database, and the corresponding variable names used in the analysis dataset, are documented in the 18 year questionnaire with coding annotations (pdf). The table below summarises the fields used in the Access database used for data entry, without going into details of field names or coding. The fields are designed to follow the layout of the qualifications page in the cohort 2 version of the 18 year questionnaire (pdf) - this page was unchanged for the cohort 3 and cohort 4 versions. The choice of data entry fields implies that certain qualification types are recorded in an approximate way - any approximations used are described under another heading below.
All data are entered in numerically coded form: for further details of the coding used, see the annotated questionnaire (pdf). Grades are entered using the codes described above (see grades). Awards are entered as the number of A-level workload equivalences (see workload equivalence above). Subjects are entered using predetermined numeric codes, which are recorded in variable value labels; see also subject coding below.
As indicated in the table, data entry allows for the recording of up to six A- or AS-levels, one level 3 NVQ, one level 3 BTEC or Advanced/Progression Diploma, one EPQ, and one "other" qualification.
| Qualification type | Data fields |
|---|---|
| A-levels and AS-levels (up to 6 may be entered) |
award, subject, grade |
| award, subject, grade | |
| award, subject, grade | |
| award, subject, grade | |
| award, subject, grade | |
| award, subject, grade | |
| Level 3 NVQ | subject |
| Level 3 BTEC and Advanced/Progression Diploma |
award, subject, grade |
| EPQ | grade |
| Other qualifications | category |
The latter field is designed simply to record the presence of certain other categories of qualification, without further details of subject, grade, etc. The categories that may be recorded here are:
- Scottish Highers
- Welsh Baccalaureate
- International Baccalaureate (IB)
- Other overseas post-16 qualifications
- Other UK level 1 or 2 qualifications
- Other UK level 3 qualifications
- A-levels with unspecified grades
Qualifications Not Entered
The qualification types described above cover a large majority of the qualifications recorded by twins on the 18 year questionnaire. However, other qualification types have not been entered in the TEDS data.
- GCSE re-takes
- Any level 2 (or level 1) qualifications
- Extra-curricular awards such as DofE, sports, music, drama and dance
- Any qualification not accredited by Ofqual, such as miscellaneous secretarial or IT certificates
- Any qualification started but not yet completed (no grade given)
- Any component module or unit results contributing to an overall examination
These are generally rare types that were recorded by a small minority of twins. Furthermore, they are generally difficult or impossible to equate to A-levels in terms of grade and workload; and even when accredited by Ofqual, they often make only a minor contribution to an individual's examination achievement.
Approximations used
The range of available qualifications at age 18 is much narrower than it was at age 16, and fewer approximations have been used in recording them. The most common qualification types at age 18 are A/AS-levels, level 3 NVQs, level 3 BTECs, Advanced/Progression Diplomas, and EPQs; all of these types are recorded with a level of detail appropriate to the type (subject, award, grade). However, approximations leading to some loss of data will occur in the following cases:
- The "other qualifications" (overseas, Scottish, etc) are recorded only in so far as they exist; no detail of subject, award or grade is recorded.
- There is only one field for recording "other qualifications", so there is no distinction between twins have one, two or more than two such qualifications.
- Qualifications below level 3 (at entry level, level 1 or level 2) are not recorded at all in the 18 year data.
- Qualifications above level 3 are not recorded at all (although these are extremely rare)
- In very rare cases, twins may have too many qualifications to be entered
in the available data fields:
- More than six separate A- or AS-levels
- More than one level 3 NVQ
- More than one level 3 BTEC or Advanced/Progression Diploma
- More than one EPQ
During the data entry process, certain assumptions must sometimes be made when a twin fails to record all the necessary details of a qualification. For the sake of consistency, these assumptions have been formalised as a set of general rules for data entry. Some of the more commonly-applied assumptions are as follows:
- If results are recorded in the same subject for both AS-level and full A-level, then only the full A-level result is recorded. This commonly arises when a twin takes an AS-level then later converts it to a full A-level with their second year of studies.
- If more than one result is recorded for the same subject (in A/AS-levels, or in other types), then only the highest-graded result is recorded. This may arise when twins re-take exams, or when they mistakenly record the same result twice.
- In any of the main qualification types except for NVQ, a grade cannot be assumed if the twin has not recorded one (so the qualification is not entered).
- In BTECs and Diplomas, if a twin does not specify the award type, then the most likely type was judged according to the number of grades recorded (e.g. two grades often means an award equivalent to two A-levels), and according to the number of other qualifications taken. In extreme cases of vagueness, the qualification was not entered.
- In the A/AS-level section, if a twin does not specify whether a result is for A or AS, then the most likely award type was judged according to the number and type of other exam results gained by the twin.
- In A/AS-levels, NVQs, BTECs and Diplomas, when an unusual subject was recorded, sometimes an existing close match was chosen rather than entering a new subject (e.g. "Health and Social Care" might be selected as the subject if a twin simply records "Health" for a BTEC)