An overview of the MCS income dataset is given in Section 3.1.2, and this dataset is analysed ex- tensively in Chapters 5 to 8. Details of the criteria for a main respondent’s inclusion in this dataset are given in Table A.2, and Table A.3 provides the source of the variables selected for this dataset. The main respondent is predominantly the cohort member’s natural mother, and there are just three exceptions in our subset of the data (two are the natural father and one the foster mother). Not all the required variables are in the UK data archive downloads, but are calculated from a number of variables which are available. Details of these calculations are also given in this section. In addition,
Tables A.4 and A.5 provide descriptions of the NVQ levels which determine the edu categories and the NS-SEC classifications behind the sc categories respectively.
Table A.2: Criteria for inclusion of record in MCS income dataset
criteria condition useda
is single in sweep 1 adresp00 = 1
has paid work in sweep 1 admwrk00 = 1
is not self-employed in sweep 1 amsepa00 < 0 and adm05s00 6= 3 has not stopped working in sweep 2 admwrk00 6= 2 and admwrk00 6= −1 is not self-employed in sweep 2 bmsepa00 < 0 and bdm05s00 6= 3
a shown in terms of the MCS eight character codes
Table A.3: Details of the source of MCS income variables
name description variable type sweep 1 codea sweep 2 codeb
hpay hourly net pay calculated see below see below
age main respondent’s age at interview derived admagi00 bdmagi00
hsize number of people in household derived adtotp00 bdtotp00 kids number of siblings in household plus number
of cohort babies
derived adtots00 bdtots00
edu main respondent’s educational level: the level of National Vocational Qualification (NVQ) equivalence of the individual’s highest aca- demic or vocational educational qualification
combinationc adnvqm00 see below
sc main respondent’s social class: National Statistics Socio-Economic Classification (NS- SEC) grouped into 5 categories
derived adm05s00 bdm05s00
eth main respondent’s ethnic group: 2 levels (white/non-white) aggregated from 6 cate- gory census classification
derived adm06e00e bdm06e00e
sing single/partner: from parent interview re- sponse summary
derived 1 by selection bdresp00f
reg residing region: 2 levels (London/other) ag- gregated from 12 category classification
admind aaregn00g baregn00g
ctry country admind aactry00 n/a
stratum stratum within country: 9 category classifi- cation
admind aaptty00 n/a
ward fieldwork point number incorporating super- wards (created by combing small wards, as described in Plewis (2007a), p.12)
admind aasptn00 n/a
a All sweep 1 variables extracted from mcs1 household grid june 2006.tab, included in the SN:4683 Millennium Cohort Study
First Survey, 2001-2003 (MCS1) download from the UK data archive.
b All sweep 2 variables extracted from mcs2 household grid june 2006.tab, included in the SN:5350 Millennium Cohort Study
Second Survey, 2003-2005 (MCS2) download from the UK data archive. All sweep 2 variables are set to missing if the main respondent changed between sweeps (bmpnum00 6= ampnum00).
c derived variable for sweep 1 and calculated for sweep 2 d survey administrative data variable
e aggregated into 2 levels: white (code 1) and non-white (codes 2-6) f aggregated into 2 levels: single (codes 1 and 7) and partner (codes 2-6) g aggregated into 2 levels: London (code 3) and other (codes 1-2 and 4-12)
Calculation of hpay
Hourly net pay, hpay, is calculated using main respondent variables taken from Module J: Employment and Education as follows:
1 Calculate annual net pay, apay, using the amount of take-home pay last time respondent paid (sweep 1: amneta00; sweep 2: bmneta00) and the time period covered by last take-home pay (sweep 1: amnetp00; sweep 2: bmnetm00).
2 Calculate the number of hours worked in a week excluding overtime, hrs, by taking the minimum of the number of hours usually worked in a week including usual overtime (sweep 1: amwkhr00; sweep 2: bmwkhr00) and 35 (assumed to be the length of a standard working week excluding lunch breaks).
3 Calculate hourly net pay assuming 46 working weeks in a year and excluding overtime, according to the formula
hpay = apay
hrs × 46.
Overtime pay is included in apay, so ideally we would exclude only unpaid overtime from hrs. Un- fortunately, we cannot distinguish between unpaid and paid overtime from the available data, so we exclude all overtime hours. Despite this inconsistency in the treatment of overtime, we consider the method adequate for the purpose of this methodological research.
Calculation of edu for sweep 2
There is no derived educational variable for sweep 2, similar to adnvqm00 for sweep 1, therefore we create one by updating adnvqm00 as follows:
1 Create a single variable, newac, indicating the highest level of new academic qualifications acquired since sweep 1 using variables bmnacq0a − bmnacq0h.
2 Create a single variable, newvo, indicating the highest level of new vocational qualifications acquired since sweep 1 using variables bmnvcq0a − bmnvcq0h.
3 Combine newac and newvo into a single variable, newqual, indicating the highest level of new academic or vocational qualifications acquired since sweep 1.
4 Take the maximum of adnvqm00 and newqual.
Note that the calculation outlined above is only valid for creating a sweep 2 educational variable for existing families where the main respondent is unchanged between sweeps. By definition our datasets only include such individuals.
Table A.4: Levels of National Vocational Qualification (NVQ) equivalence
edu category NVQ level description
5 NVQ5 Higher degree
4 NVQ4 Diploma in higher education; First degree; Nursing/other medical qual- ification; Professional qualification at degree level
3 NVQ3 A/AS/S levels; NVQ/SVQ/GSVG level 3
2 NVQ2 O level/GSCE grades A-C; NVQ/SVQ/GSVG level 2; Trade appren- ticeships
1 NVQ1 GSCE grades D-G; NVQ/SVQ/GSVG level 1 0 None None of these qualifications
Table A.5: National Statistics Socio-Economic Classification (NS-SEC) sc category NS-SEC classification description
1 1 Managerial and Professional occupations
2 2 Intermediate occupations
n/a 3 Small employers and own account workers
3 4 Lower supervisory and technical occupations
4 5 Semi-routine and routine occupations