Table 1

Description of variables used in this study
Variable Levels Description
Health outcomes
Self-reported health (SRH) Good health - 0 · General health rated as very good, good, fair, bad or very bad
Poor health −1 · Good health recoded as very good or good
· Poor health recoded as fair, bad, very bad
Limiting longstanding illness (LLI) No LLI - 0 Respondents asked if they had a limiting-longstanding illness
LLI - 1 · No LLI
· Have LLI
Mental health Good mental health - 0 Score from the 12-item General Health Questionnaire (GHQ-12).
Poor mental health - 1 · Score 0–3 recoded as good mental health
· Score 4 or more recoded as poor mental health
Lung function Good lung function - 0 Three questions related to respiratory symptoms were asked resulting in the variable ‘wheezed without a cold’.
Poor lung function - 1 · Not ‘wheezed without a cold’ recoded as good lung function
· ‘Wheezed without a cold’ recoded poor lung function
Smoking status Non-smoker - 0 Smoking history
Smoker - 1 · Non-smoker
· Current smoker
Alcohol consumption Under and including limits - 0 Weekly alcohol consumption (weekly limits: males 21 units, females 14 units)
Over weekly limits - 1 · Under and including limits
·` Over weekly limits
Explanatory variable
Employment status Employed −1 Employment status at time of interview
Unemployed - 2
Permanently sick - 3
Looking after home and family - 4
Others – 5
Confounding variables
Sex Male – 1 Sex of the respondent
Female – 2
Age 16-24 - 1 Age of respondent
25–34 - 2
35–44 - 3
45–54 - 4
55–64 - 5
Deprivation (SIMD quintile) Scale 1 to 5 The Scottish Index of Multiple Deprivation (SIMD), an area-based level of deprivation, was derived from the residential postcode of the respondents and categorised into quintiles. The SIMD score is calculated at the level of “data zones” using 31 indicators in six individual domains of current income, employment, housing, health, education, skills and training and geographic access to services and telecommunications. Data zones are groups of Census output areas which have populations of between 500 and 1,000 residents.
Least deprived - 1
Most deprived - 5
Education Degree or higher −1 Highest level of qualification obtained
Higher National Certificate/Diploma (HNC/D) or equivalent - 2
Higher grade or equivalent - 3
Standard grade or equivalent - 4
Other school level - 5
None - 6

Brown et al.

Brown et al. BMC Public Health 2012 12:327   doi:10.1186/1471-2458-12-327

Open Data