Appendix A: Variables used in the analysis
Equivalised annual household income (quintiles)
The income that a household needs to attain a given standard of living will depend on its size and composition. For example, a couple with dependent children will need a higher income than a single person with no children to attain the same material living standards. 'Equivalisation' means adjusting a household's income for size and composition so that we can look at the incomes of all households on a comparable basis.
After equivalisation, the sample was split into five, equally sized groups - or quintiles - according to income distribution. Each group thus contains around 20% of families. (For the regression a separate category was created for cases with missing information.)
Area deprivation (SIMD)
Area deprivation is measured using the Scottish Index of Multiple Deprivation (SIMD) which identifies small area concentrations of multiple deprivation across Scotland. It is based on 37 indicators in the seven individual domains of Current Income, Employment, Health, Education Skills and Training, Geographic Access to Services (including public transport travel times for the first time), Housing and a new Crime Domain. SIMD is presented at data zone level, enabling small pockets of deprivation to be identified. The data zones, which have a median population size of 769, are ranked from most deprived (1) to least deprived (6,505) on the overall SIMD and on each of the individual domains. The result is a comprehensive picture of relative area deprivation across Scotland.
In this report, data zones are grouped into quintiles according to their SIMD score. Quintiles are percentiles which divide a distribution into fifths, i.e., the 20th, 40th, 60th, and 80th percentiles. Those respondents whose postcode falls into the first quintile are said to live in one of the 20% least deprived areas in Scotland. Those whose postcode falls into the fifth quintile are said to live in one of the 20% most deprived areas in Scotland.
Further details on SIMD can be found on the Scottish Government website: http://www.scotland.gov.uk/Topics/Statistics/SIMD/Overview
Highest household level of education
At the first wave of data collection for both cohorts, parents were asked to provide information on the nature and level of any school and post-school qualifications they had obtained. This information was obtained for up to two adults in the household (the main adult respondent and, where applicable, their partner) and was updated at each subsequent contact. Qualifications were grouped according to their equivalent position on the Scottish Credit and Qualifications Framework which ranges from Access 1 to Doctorate. For the purposes of the analysis carried out in chapter 3, these were further banded to create the following categories:
- Lower Standard Grades and below (incl no formal qualifications)
- Upper Standard Grades and intermediate VQs
- Higher Grades, Upper Level VQs and 'Other'
The regression analysis reported in chapter 4 used a measure banded into just two categories:
- Below degree (incl. cases with missing information)
The highest qualification was defined for each parent and a household level variable was calculated. In couple families this corresponds to the highest qualification among the respondent and his/her partner.
The Scottish Government Urban Rural Classification was first released in 2000 and is consistent with the Government's core definition of rurality which defines settlements of 3,000 or less people to be rural. It also classifies areas as remote based on drive times from settlements of 10,000 or more people. The definitions of urban and rural areas underlying the classification are unchanged.
The classification has been designed to be simple and easy to understand and apply. It distinguishes between urban, rural and remote areas within Scotland and includes the following categories:
- 'Large Urban Areas': Settlements of 125,000 people or more
- 'Other Urban Areas': Settlements of 10,000 to 124,999 people
- 'Accessible Small Towns': Settlements of between 3,000 and 9,999 people and within 30 minutes' drive of a settlement of 10,000 or more
- 'Remote Small Towns': Settlements of between 3,000 and 9,999 people and with a drive time of over 30 minutes to a settlement of 10,000 or more
- 'Accessible Rural': Settlements of less than 3,000 people and within 30 minutes' drive of a settlement of 10,000 or more
- Remote Rural': Settlements of less than 3,000 people and with a drive time of over 30 minutes to a settlement of 10,000 or more
For further details on the classification see the Scottish Government's website: http://www.gov.scot/Topics/Statistics/About/Methodology/UrbanRuralClassification?um_source=website&utm_medium=navigation&utm_campaign=statisticsevaluationtools
For the purposes of this report, the above were banded into two categories:
- Urban (large and other urban areas, incl. cases with missing information)
- Small town and rural (accessible small towns, accessible rural, remote small towns, remote rural).
Languages spoken in household
Whether other languages than English were spoken in the household at the time of the sweep 5 (age 5) interview. (Cases with missing information were added to the 'English only' category.)
At sweep 4 (at the time the cohort child was aged just under 4), the child's main carer was asked two questions designed to measure difficulties with reading and writing. At each question they were asked to indicate whether they had any difficulties with specific tasks. For example, in relation to reading these included understanding what is written in a newspaper and reading aloud from a children's storybook; for writing they included spelling words correctly and making handwriting easy to read.
Responses across all items were combined into a single binary variable indicating whether the child's main carer had any literacy issues. (Cases with missing information were added to the 'No literacy issues' category.)
Parent mental wellbeing
The main carer's mental wellbeing was measured using the Short-Form-12 scale which comprises a physical and a mental wellbeing scale. Data on this measure were collected when the child was aged just under 5 (sweep 5) and when they were in Primary 6 (sweep 8). At each time point, a standardised score was derived which identified those with below average mental wellbeing.
A combined measure then identified those who had below average mental wellbeing at either one or both of the two time points. (Cases with missing information were added to the 'Average or above average' category.)
Parent limiting health problem
Whether the cohort child's main carer reported a limiting long-term health problem at either of the two time points considered in the analysis - i.e. when they were just under 5 (sweep 5) and when they were in Primary 6 (sweep 8). (Cases with missing information were added to the 'No limiting health problem' category.)
Whether the cohort child changed school between the time they started school and the time of their GUS sweep 8 (Primary 6) interview. (Cases with missing information were added to the 'Did not change school' category.)
Change in family type
Whether there was a difference in family type at the two time points considered - when child was aged just under 5 and when they were in Primary 6.
- 'Stable family type': couple or single parent household at both sweeps (incl. cases with missing information)
- 'Change in family type': couple household at one sweep; single parent household at the other.
Significant event happened
Whether the child experienced any of the following events between sweep 5 and sweep 8:
- Death of parent or sibling
- Parent in prison
- Child spent time in care
- Parent lost job
(Cases with missing information were added to the 'No significant changes' category.)
Child limiting health problem
Whether the child was reported by their main carer as having a limiting long-term health problem at either of the two time points considered in the analysis - i.e. when they were just under 5 (sweep 5) and when they were in Primary 6 (sweep 8). (Cases with missing information were added to the 'No limiting health problems' category.)
Child level of social, emotional, behavioural difficulties
On GUS, measures of social, emotional and behavioural development are routinely obtained using items from the Strengths and Difficulties Questionnaire (SDQ) (Goodman, 1997). A parent report version of the SDQ was included in the self-completion section of the age 5 interview.
The SDQ is a commonly used behavioural screening questionnaire designed for use with children aged between 3 and 16. It consists of 25 questions about a child's behaviour, to which the respondent can answer 'not true', 'somewhat true' or 'certainly true'. Responses can be combined to form five different measures of the child's development, namely emotional symptoms (e.g. excessive worrying), conduct problems (e.g. often fighting with other children), hyperactivity/inattention (for example, constantly fidgeting), peer relationship problems (e.g. not having close friends) and pro-social behaviour (e.g. being kind to others). Furthermore, the first four measures can be combined into a 'total difficulties' scale.
In this report, a measure of the total difficulties score is used. It was banded using recommended cut-off points. Previously, SDQ scores were most commonly divided into 'normal', 'borderline' and 'abnormal' scores. These bandings were reviewed in 2016 and it is now recommended that SDQ scores on each of the scales are divided into the following categories: 'close to average', 'slightly raised', 'high' and 'very high', with 'very high' indicating multiple problems identified.
The measure used in the report further banded these into two categories:
- Average levels of difficulties ('close to average') (incl. cases with missing information)
- Above average levels of difficulties ('slightly raised', 'high' and 'very high').
Warmth of parent-child relationship
Seven items from the Pianta parent-child relationship scale were used to create a composite measure of the warmth of the parent-child relationship. The child's main carer was asked each item below in the self-completion section of the sweep 7 interview, undertaken just before the child's eighth birthday. For each item the answer options were 'definitely does not apply', 'not really', 'neutral', 'applies sometimes', 'definitely does not apply'.
The following items were used to create the score:
- I share an affectionate, warm relationship with [child]
- [Child] will seek comfort from me
- [Child] values his/her relationship with me
- When I praise [child] he/she beams with pride
- [Child] spontaneously shares information about him/herself
- It is easy to be in tune with what [child] is feeling
- [Child] openly shares his/her feelings and experiences with me
Reliability analysis showed a good internal consistency (alpha = 0.706).
The score was then divided into two categories which were used in the analysis:
- Higher level of warmth
- Lower level of warmth (incl. cases with missing information).
As part of the sweep 7 interview, when the cohort child was just under 8 years old, the main carer was asked if they had attended one or more of the activities listed below in the last approximately two years since their last GUS interview:
- Attending parent evening
- Visiting child's classroom
- Volunteering in school classroom, library, office
- Volunteering for school trip or event
- Offering to volunteer but not asked
- Attending school event where child participated
- Attending school event where child did not participate
- Attending parent council, PTA or school board meeting
- Attending open meeting
- Helping with fundraising
A score was created by adding up the number of activities the parent/carer had attended, which was then banded into the following categories:
- High (7-10 activities)
- Low-Medium (6 activities or less) (incl. cases with missing information).
How often parent helps child look for school-related information
As part of the sweep 7 interview, the child's main carer was asked 'How often do you help [child] look for information about what ^he is learning at school, for example at the library or on the internet?', with answer options 'most days', 'at least once a week', 'a few times a month', 'about once a month', 'a few times a year', 'less often than a few times a year' and 'never'.
The measure used in the analysis had two categories:
- Most days
- Less often (incl. cases with missing information)
As part of the sweep 7 interview, the main carer was also asked 'How many days in the last week has [child] looked at books or read stories at home?'
Answers were banded into two categories:
- 6-7 days
- 5 days or less (incl. cases with missing information).
Parent belief in ability to influence child's achievements at school
At sweep 7 the main carer was also asked to what extent they agreed or disagreed with the following statement: 'I believe I can positively influence my child's achievement at school'. Answer categories went from 'Agree strongly' to 'disagree strongly' on a five-point scale. For analysis purposes, the question was coded into two categories:
- Highly positive (agree strongly)
- Less positive (agree, neither agree nor disagree, disagree/disagree strongly, and cases with missing information).
Child's feelings about school
As part of the sweep 7 interview, the child answered a small number of questions on the survey interviewer's laptop. These included three items related to how they felt about school:
- I look forward to going to school
- I hate school
- I enjoy learning at school
Each item had answer options 'never', 'sometimes', 'often', 'always'. The three items were combined into a composite score (internal consistency was good, alpha=0.783) which was then divided into two categories:
- Highly positive (most positive score on all three items)
- Less positive (incl. cases with missing information).
Linked school data
Chapter 4 uses administrative data about the child's Primary 1 school. Consent to link the children's GUS survey data to administrative data - held by the Scottish Government - was obtained from the child's parent or guardian at the 6th sweep of face-to-face data collection, when the child was aged just under 6 years (in 2010/11). Parents/guardians who did not consent at sweep 6, or those who missed an interview at sweep 6, were asked for consent at sweep 7. Consent was captured on a written consent form.
3534 parents (out of 3657, 97%) gave permission to link their survey data with education administrative data at sweep 6. A further 100 (out of 157, 64%) consented at sweep 7. Overall, 3634 of 3814 asked gave consent - 95%. Out of those who consented, 3365 (95%) were successfully matched to education records held by ScotXEd.
After providing the data from GUS, cases were matched by ScotXEd. Matching was done on a sequential basis using all available data and matching to both the 2009 and 2010 pupil census datasets.
Two separate datasets are available: a pupil-level and a school-level dataset. Both datasets contain information relevant to when the GUS children were in Primary 1.
Because children in BC1 straddle two school years, the data in the Primary 1 datasets were not all obtained in the same year - for around three-quarters of children data were obtained for the 2009/10 school year. For the remaining quarter, data were obtained for the 2010/11 school year.
This report uses the following measures:
Size of school: count of the number of pupils enrolled in the school banded as follows:
- Over 400
- [No information].
Proportion of children registered for free school meals: the proportion of pupils in the school registered for free school meals. For the analysis, this measure was split into two categories:
- More than 25%
- 25% or less
In addition, a separate category was created for cases with no information.
Whether denominational school: whether the school was registered as a denominational (faith) school. (Cases with no information were added to the 'No denomination' category).