| dataset variable name | rawdata variable name | dataset
variable label | item or derived variable? | data type |
variable level | coding or approximate range of values |
|---|
| aadults | - | Household type: adults present (1st
Contact), see value labels | derived | integer | nominal |
1=cohabiting biological mother and father, 2=cohabiting biological parent with other,
3=single parent, 4=biological mother with missing partner details, 9=unknown or other |
|---|
| aalgzyg | - | Zygosity derived from questionnaire and twin
sexes (1st Contact), see value labels | derived | integer |
nominal | 1=MZ, 2=DZ, 5=unknown mid-range, 99=unknown conflicting |
|---|
| aalg2zy | - | Zygosity derived from questionnaire only (1st
Contact), see value labels | derived | integer | nominal |
1=MZ, 2=DZ, 5=unknown mid-range, 99=unknown conflicting |
|---|
| aaloneh1/2 | dd45, dd46 | Hours per week that
twin spends alone with you (1st Contact), see value labels | item |
integer | ordinal | 0=0, 1=up to 1, 2=1-2, 3=2-6, 4=6-20, 5=20-40, 6=over 40 (hours/week) |
|---|
| aapart | dd47 | Twins ever apart for more than half an hour
(1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| abcomp | mp39 | Complications during birth (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| abcompc | mp40code | Type of complication during birth, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=breech or position problem, 2=cord or placenta problem, 3=twin medical issues, 4=maternal medical issues,
5=forceps or ventouse delivery, 6=other or unspecific problems |
|---|
| abdrug | mp37 | Given drugs during labour (1st Contact), 1Y 0N |
item | integer | nominal | 0=no, 1=yes |
|---|
| abdrugc | mp38code | Type of drug given during labour, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=general anaesthetic, 2=spinal block, 3=epidural, 4=opioids or other injection,
5=gas and air, 6=other or unspecified drug |
|---|
| abed1par | dd31 | One parent usually puts twins to bed (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| abed2par | dd32 | Both parents usually put twins to bed (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| abedfrnd | dd34 | Friends usually put twins to bed (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| abedprof | dd35 | Professional carer usually puts twins to
bed (1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| abedrel | dd33 | Relatives usually put twins to bed (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| abgap | mp43 | Gap between births in minutes (1st
Contact), see value labels | item | integer |
ordinal | 1=1 minute or less, 2=2-5, 3=6-10, 4=11-15, 5=16-20, 6=21-30, 7=over 30 minutes |
|---|
| ablen1/2 | mp44cm, mp45cm | Length of twin at
birth (1st Contact), number of centimetres | item | integer |
quantitative | approx. 26 to 62 (centimetres) |
|---|
| abotfdd1/2 | dd07, dd08 |
For how long was twin fed breast milk by bottle (1st Contact), see value labels |
item | integer | ordinal |
0=0, 1=1-7, 2=8-30, 3=31-60, 4=61-180, 5=181-360, 6=361 or more days |
|---|
| abotfed1/2 | dd06 | Was twin fed breast milk by bottle (1st
Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| abprob1/2 | mp52, mp53 | Concerns about problems at birth of
twin (1st Contact), 1Y 0N | item | integer |
nominal | 0=no, 1=yes |
|---|
| abprobc | mp54code | Type of concern about problem at birth, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=breathing, 2=jaundice/blood, 3=heart, 4=premature, 5=breech or limb, 6=inhaled fluid,
7=resuscitated, 9=other |
|---|
| abrstfdd1/2 | dd04, dd05 |
For how long was twin breast fed (1st Contact), see value labels |
item | integer | ordinal |
0=0, 1=1-7, 2=8-30, 3=31-60, 4=61-180, 5=181-360, 6=361 or more days |
|---|
| abrstfed1/2 | dd03 | Was twin ever breastfed (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| acaes | mp41 | Birth by caesarean section (1st Contact), see value labels |
item | integer | nominal | 0=no,
1=yes expected, 2=yes emergency |
|---|
| acaesc | mp42code | Reason for caesarean section, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=breech or position problem, 2=cord or placenta problem, 3=twin medical issues, 4=maternal medical issues,
5=precautionary reasons, 6=other or unspecified problem |
|---|
| acontact | - | 1st Contact data is present, 1Y 0N |
derived | integer | nominal | 0=no, 1=yes |
|---|
| adadagetw | - | Age in years of natural father at time of
birth of twins | derived | decimal | quantitative |
approx. 16 to 65 (years) |
|---|
| adadage | - | Age in years of natural father at time of 1st
Contact | derived | decimal | quantitative | approx. 18 to 65 (years) |
|---|
| adiet | mp13 | On special diet while pregnant (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| adietc | mp14code | Type of special diet while pregnant, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=meat-free, 2=healthy diets |
|---|
| adresdif | dd26 | Can tell twins apart by their dress (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| adressim | dd19 | Do you dress twins similarly (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| adrink | mp15 | Drank alcohol while pregnant (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| adrink1x | mp16 | Drank alcohol first three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| adrink2x | mp17 | Drank alcohol middle three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| adrink3x | mp18 | Drank alcohol last three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| adrinknu | mp19 | Number of alcohol units per week while
pregnant (1st Contact), see value labels | item | integer | ordinal |
0=0, 1=1, 2=2, 3=3, 4=4-5, 5=6-7, 6=8-13, 7=14 or more |
|---|
| adscheap | dd23 | Dress similarly: cheaper (1st Contact), 1Y
0N | item | integer | nominal | 0=no, 1=yes |
|---|
| adseasy | dd22 | Dress similarly: easier (1st Contact), 1Y
0N | item | integer | nominal | 0=no, 1=yes |
|---|
| adsgiven | dd24 | Dress similarly: given matching clothes
(1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| adslike | dd21 | Dress similarly: twins like to look the
same (1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| adsmatch | dd20 | Dress similarly: like twins to match (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| aethnic | yt07 | Ethnic origin of twins, simplified coding (1st Contact),
1=white 0=other | item | integer | nominal |
0=other, 1=white |
|---|
| aethnicc | yt07 | Ethnic origin of twins, original categories (1st Contact),
see value labels | item | integer | nominal |
1=Asian, 2=Black, 3=Mixed race, 4=White, 5=Other |
|---|
| afaclas | - | Male parent social class employment level (1st
Contact), 1-6 | derived | integer | ordinal |
1=professional, 2=managerial, 3=skilled non-manual, 4=skilled manual,
5=partly skilled, 6=unskilled |
|---|
| afahqual | - | Male parent highest qualification level (1st
Contact), see value labels | derived | integer | ordinal |
1=none, 2=O/GCSE grade D-G or CSE grade 2-5, 3=O/GCSE grade A-C or CSE grade
1, 4=A/S level, 5=HNC, 6=HND, 7=undergraduate degree, 8=postgrad |
|---|
| afajob | - | Male parent has a job (1st Contact), see value
labels | derived | integer | nominal | 0=no, 1=yes,
2=staying at home to look after children |
|---|
| afasoc | - | Male parent SOC employment level (1st Contact),
1-9 | derived | integer | ordinal | 1=manager,
2=professional, 3=technical, 4=clerical, 5=craft, 6=personal, 7=sales,
8=plant, 9=unskilled |
|---|
| afaspq | - | Male parent needs special qualifications for
job (1st Contact), see value labels | derived | integer |
nominal | 0=no, 1=yes, 2=dont know |
|---|
| afawork | - | Male parent job type (1st Contact), see value
labels | derived | integer | nominal | 1=manager,
2=employee, 3=self employed with employees, 4=foreman, 5=apprentice, 6=self
employed no employees |
|---|
| afeedgap | dd17, dd18 | Gap between feeding twins
(1st Contact), see value labels | item | integer |
ordinal | 0=fed together (less than 5 minutes), 1=1-15, 2=16-59, 3=60+ minutes |
|---|
| afert | mp01 | Mother had fertility treatment (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| afertc | mp02code | Type of fertility treatment, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=IVF, 2=IUI, 3=drugs/hormones |
|---|
| afits1/2 | mp76, mp77 | Twin has had fits (1st Contact), see
value labels | item | integer | nominal | 0=no,
1=yes without temperature, 2=yes with high temperature |
|---|
| afrndfee | dd11 | Friends feed the twins (1st Contact), 1Y
0N | item | integer | nominal | 0=no, 1=yes |
|---|
| afussy1/2 | dd16 | Is twin a fussy eater (1st Contact), 1Y
0N | item | integer | nominal | 0=no, 1=yes |
|---|
| agenpro1/2 | mp72 | Twin has genetic problems (1st Contact),
1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| agestage | mp33 | Gestation age for twins in weeks (1st Contact),
see value labels | item | integer | ordinal |
26=26 or lower, 27, 28, ... 40, 41, 42=42 or higher (weeks) |
|---|
| ahand1/2 | mp78, mp79 | Which hand does twin use (1st
Contact), see value labels | item | integer | ordinal |
1=always right, 2=usually right, 3=either, 4=usually left, 5=always left |
|---|
| ahcatar1/2 | h05, h06 | Twin gets catarrh during a cold (1st
Contact), see value labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahcold1/2 | h03, h04 | Twin has hearing diffulties during a
cold (1st Contact), see value labels | item | integer |
ordinal | 0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahmouth1/2 | h13, h14 | Twin breathes through mouth (1st
Contact), see value labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahospd1/2 | mp60, mp61 |
Number of days twin stayed in hospital after birth (1st Contact), see value labels |
item | integer | ordinal | 1=0-3, 2=4-5, 3=6-7, 4=8-14, 5=15-30, 6=31-74, 7=75 or more days |
|---|
| ahprob1/2 | h01, h02 | Twin has suspected hearing problem
(1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| ahpus1/2 | h11, h12 | Twin has had pus in ears (1st
Contact), see value labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahscrat1/2 | h07, h08 | Twin scratches ears (1st Contact),
see value labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahsnore1/2 | h15, h16 | Twin snores (1st Contact), see value
labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ahsore1/2 | h09, h10 | Twin has sore ears (1st Contact), see
value labels | item | integer | ordinal |
0=never, 1=occasionally, 2=sometimes, 3=often |
|---|
| ainduced | mp35 | Was labour induced (1st Contact), 1Y 0N |
item | integer | nominal | 0=no, 1=yes |
|---|
| akidgr1/2 | mp48kg, mp49kg |
Weight of twin at birth (1st Contact), number of grams | item |
integer | quantitative | approx. 400 to 4200 (grams) |
|---|
| alabourh | mp36 | Length of labour in hours (1st Contact),
see value labels | item | integer | ordinal |
0=0, 1=1-2, 2=3-4, 3=5-6, 4=7-8, 5=9-10, 6=11-12, 7=13-16, 8=17-24, 9=over 24 hours |
|---|
| alang | yt08 | Main language spoken at home (1st Contact),
see value labels | item | integer | nominal |
0=other, 1=English, 2=English+other |
|---|
| aLLCage | - | Age in months of twins at time of 1st Contact (for use in LLC TRE) |
derived | integer | quantitative |
approx. 11 or higher (months) |
|---|
| aLLCdate | - | Date of 1st Contact booklet return (for use in LLC TRE), yyyy-mm string |
derived | string | date value |
approx. '1995-11' or later |
|---|
| alookels | dd43 | Twins looked after by anyone else (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| alookfrn | dd41 | Twins looked after by friends (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| alookh | dd44 | How long are twins looked after by
others each week (1st Contact), see value labels | item | integer |
ordinal | 1=1 hour or less, 2=1-2 hours, 3=2-4 hours, 4=4-10 hours,
5=10-20 hours, 6=20-40 hours, 7=over 40 hours |
|---|
| alookpar | dd39 | Twins looked after by other parent (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| alookpro | dd42 | Twins looked after by professional carer
(1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| alookrel | dd40 | Twins looked after by relatives (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| amagechl | - | Age in years of mother at birth of first
child, corrected (1st Contact) | derived | decimal |
quantitative | approx. 13 to 45 (years) |
|---|
| ameds | mp03 | Regular medicine while pregnant (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| ameds1x | mp04 | Regular medicine first three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| ameds2x | mp05 | Regular medicine middle three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| ameds3x | mp06 | Regular medicine last three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| amedsc | mp07code | Type of medicine taken while pregnant, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=folic acid and/or iron, 2=other medicines |
|---|
| amedtot | - | Mother medical risk factor composite scale
(1st Contact), standardised | derived | decimal | scale
value | approx. -2 to +4 (standardised) |
|---|
| amoclas | - | Female parent social class employment level
(1st Contact), 1-6 | derived | integer | ordinal |
1=professional, 2=managerial, 3=skilled non-manual, 4=skilled manual,
5=partly skilled, 6=unskilled |
|---|
| amohqual | - | Female parent highest qualification level
(1st Contact), see value labels | derived | integer |
ordinal | 1=none, 2=O/GCSE grade D-G or CSE grade 2-5, 3=O/GCSE grade
A-C or CSE grade 1, 4=A/S level, 5=HNC, 6=HND, 7=undergraduate degree,
8=postgrad |
|---|
| amojob | - | Female parent has a job (1st Contact), see
value labels | derived | integer | nominal | 0=no,
1=yes, 2=staying at home to look after children |
|---|
| amosoc | - | Female parent SOC employment level (1st
Contact), 1-9 | derived | integer | ordinal |
1=manager, 2=professional, 3=technical, 4=clerical, 5=craft, 6=personal,
7=sales, 8=plant, 9=unskilled |
|---|
| amospq | - | Female parent needs special qualifications for
job (1st Contact), see value labels | derived | integer |
nominal | 0=no, 1=yes, 2=dont know |
|---|
| amowork | - | Female parent job type (1st Contact), see
value labels | derived | integer | nominal |
1=manager, 2=employee, 3=self employed with employees, 4=foreman,
5=apprentice, 6=self employed no employees |
|---|
| amprob1/2 | mp68 | Twin had medical problems within two
weeks of birth (1st Contact), 1Y 0N | item |
integer | nominal | 0=no, 1=yes |
|---|
| amprobc | mp69code | Type of medical problem, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=heart, 2=respiratory, 3=feeding, 4=jaundice, 5=infection, 6=surgery/abnormality,
7=prematurity, 8=blood-related, 9=other |
|---|
| amumagetw | - | Age in years of natural mother at time of
birth of twins | derived | decimal | quantitative |
approx. 14 to 45 (years) |
|---|
| amumage | - | Age in years of natural mother at time of 1st
Contact | derived | decimal | quantitative | approx. 16 to 60 (years) |
|---|
| anoldfsi | dd51 | Number of older female siblings (1st
Contact), see value labels | item | integer | ordinal |
0=0, 1=1, 2=2, 3=3, 4=4 or more |
|---|
| anoldmsi | dd49 | Number of older male siblings (1st
Contact), see value labels | item | integer | ordinal |
0=0, 1=1, 2=2, 3=3, 4=4 or more |
|---|
| anoldsib | dd49, dd51 | Number of older siblings (1st
Contact), see value labels | item | integer | ordinal |
0=0, 1=1, 2=2, 3=3, 4=4, 5=5 or more |
|---|
| anyngfsi | dd50 | Number of younger female siblings (1st
Contact) | item | integer | ordinal | 0=0, 1=1, 2=2 or more |
|---|
| anyngmsi | dd48 | Number of younger male siblings (1st
Contact) | item | integer | ordinal | 0=0, 1=1, 2=2 or more |
|---|
| anyngsib | dd48, dd50 | Number of younger siblings (1st
Contact) | item | integer | ordinal | 0=0, 1=1, 2=2 or more |
|---|
| aothfeedf | dd14, dd15 | How often have others fed the twins
(1st Contact), see value labels | item | integer | ordinal |
0=never, 1=once a week, 2=2-3 times a week, 3=over 3 times a week,
4=once a day, 5=2-3 times a day, 6=over 3 times a day |
|---|
| aoutp1/2 | mp62, mp63 | Twin has returned to hospital as
outpatient (1st Contact), 1Y 0N | item | integer |
nominal | 0=no, 1=yes |
|---|
| aoutpc | mp64code | Reason for outpatient visits, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=breathing, 2=infection, 3=routine follow-up, 4=hernia, 5=ear/hearing, 6=eye/vision, 7=limbs, 8=heart |
|---|
| aover1/2 | mp65, mp66 | Twin has returned to hospital to
stay overnight (1st Contact), 1Y 0N | item | integer |
nominal | 0=no, 1=yes |
|---|
| aoverc | mp67code | Reason for overnight admission, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=breathing, 2=infection, 3=convulsions, 4=surgery, 5=accident/injury, 6=other |
|---|
| aparfeed | dd09 | Other parent feeds the twins (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| apartage | - | Age in years of partner at time of 1st
Contact | derived | decimal | quantitative | approx. 18 to 65 (years) |
|---|
| apartclas | ia38b | Partner social class employment level
(1st Contact), 1-6 | item | integer | ordinal |
1=professional, 2=managerial, 3=skilled non-manual, 4=skilled manual,
5=partly skilled, 6=unskilled |
|---|
| aparthqual | - | Partner highest qualification level
(1st Contact), see value labels | item | integer |
ordinal | 1=none, 2=O/GCSE grade D-G or CSE grade 2-5, 3=O/GCSE grade
A-C or CSE grade 1, 4=A/S level, 5=HNC, 6=HND, 7=undergraduate degree,
8=postgrad |
|---|
| apartjob | ia37 | Partner has a job (1st Contact), see value
labels | item | integer | nominal | 0=no, 1=yes,
2=staying at home to look after children |
|---|
| apartrel | ia23 | Partner relationship to twins (1st
Contact), see value labels | item | integer | nominal |
1=mother, 2=father, 3=guardian or other |
|---|
| apartsex | ia22 | Partner sex (1st Contact), 0F 1M |
item | integer | nominal | 0=female, 1=male |
|---|
| apartsoc | ia38a | Partner SOC employment level (1st
Contact), 1-9 | item | integer | ordinal |
1=manager, 2=professional, 3=technical, 4=clerical, 5=craft, 6=personal,
7=sales, 8=plant, 9=unskilled |
|---|
| apartspq | ia39 | Partner needs special qualifications for
job (1st Contact), 1Y 0N | item | integer |
nominal | 0=no, 1=yes |
|---|
| apartwork | ia41 | Partner job type (1st Contact), see value
labels | item | integer | nominal | 1=manager,
2=employee, 3=self employed with employees, 4=foreman, 5=apprentice, 6=self
employed no employees |
|---|
| aperi1x | - | Perinatal outlier: low birthweight (1st
Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| aperi2x | - | Perinatal outlier: long special care when born
(1st Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| aperi3x | - | Perinatal outlier: long hospital stay after
birth (1st Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| aperi4x | - | Perinatal outlier: short gestational age (1st
Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| aperi5x | - | Perinatal outlier: high maternal drinking while
pregnant (1st Contact), 1Y 0N | derived | integer |
nominal | 0=no, 1=yes |
|---|
| aperinat | - | Perinatal outlier overall exclusion (1st
Contact), 1Y 0N | derived | integer | nominal |
0=no, 1=yes |
|---|
| aphys1/2 | mp70 | Twin has physical problems (1st Contact),
1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| aphysc | mp71code | Type physical problem, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=heart, 2=limb/skeletal, 3=internal organ, 4=head/face, 5=genitourinary, 6=other |
|---|
| apreg | dd76 | Is twins mother pregnant (1st Contact), 1Y 0N |
item | integer | nominal | 0=no, 1=yes |
|---|
| aproffee | dd12 | Professional carers feed the twins (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| arelfeed | dd10 | Other relatives feed the twins (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| arespage | - | Age in years of respondent at time of 1st
Contact | derived | decimal | quantitative | approx. 16 to 65 (years) |
|---|
| arespclas | ia17b | Respondent social class employment level
(1st Contact), 1-6 | item | integer | nominal |
1=professional, 2=managerial, 3=skilled non-manual, 4=skilled manual,
5=partly skilled, 6=unskilled |
|---|
| aresphqual | - | Respondent highest qualification level
(1st Contact), see value labels | item | integer |
ordinal | 1=none, 2=O/GCSE grade D-G or CSE grade 2-5, 3=O/GCSE grade
A-C or CSE grade 1, 4=A/S level, 5=HNC, 6=HND, 7=undergraduate degree,
8=postgrad |
|---|
| arespjob | ia16 | Respondent has a job (1st Contact), see
value labels | item | integer | nominal | 0=no,
1=yes, 2=staying at home to look after children |
|---|
| aresprel | ia02 | Respondent relationship to twins (1st
Contact), see value labels | item | integer | nominal |
1=mother, 2=father, 3=guardian or other |
|---|
| arespsex | ia01 | Respondent sex (1st Contact), 0F 1M |
item | integer | nominal | 0=female, 1=male |
|---|
| arespsoc | ia17a | Respondent SOC employment level (1st
Contact), 1-9 | item | integer | ordinal |
1=manager, 2=professional, 3=technical, 4=clerical, 5=craft, 6=personal,
7=sales, 8=plant, 9=unskilled |
|---|
| arespspq | ia18 | Respondent needs special qualifications for
job (1st Contact), 1Y 0N | item | integer |
nominal | 0=no, 1=yes |
|---|
| arespstat | ia21 | Respondent marital status (1st Contact),
see value labels | item | integer | nominal |
1=cohabiting with parent, 2=cohabiting with other, 3=divorced, 4=separated,
5=widowed, 6=unmarried |
|---|
| arespwork | ia20 | Respondent job type (1st Contact), see
value labels | item | integer | nominal | 1=manager,
2=employee, 3=self employed with employees, 4=foreman, 5=apprentice, 6=self
employed no employees |
|---|
| arestc | mp23code | Reason for bed rest during pregnancy, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=bleeding, 2=blood pressure, 3=pre-eclampsia, 4=risk of miscarriage,
5=early labour, 6=maternal illness or pain, 7=concern about embryos, 8=unspecified rest or tiredness |
|---|
| arestdd | mp22, mp24 | Prescribed
bed rest during pregnancy (1st Contact), see value labels | item | integer |
ordinal | 0=no, 1=1-7 days, 2=8-14 days, 3=15-30 days, 4=31-60 days, 5=over 60 days |
|---|
| ases | - | SES composite scale (1st Contact), standardised |
derived | decimal | scale value | approx. -2 to +2
(standardised) |
|---|
| asharerm | dd27 | Twins share a room at night (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| asibalon | dd73 | Older sibs spend time alone with you (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asibatt | dd74 | Older sibs got less attention (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asibcare | dd71 | Older sibs cared for twins (1st Contact),
1Y 0N | item | integer | nominal | 0=no, 1=yes |
|---|
| asibch | dd69 | Older sibs changed when twins born (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asibgeto | dd72 | Older sibs get on with twins (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asick1x | mp25 | Amniocentesis during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| asick2x | mp26 | High blood pressure during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| asick3x | mp27 | Diabetes during pregnancy (1st Contact), see
value labels | item | integer | nominal | 0=no,
1=yes |
|---|
| asick4x | mp28 | Toxaemia or pre-eclampsia during pregnancy
(1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| asick5x | mp29 | Vaginal bleeding during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| asick6x | mp30 | Rubella during pregnancy (1st Contact), see
value labels | item | integer | nominal | 0=no,
1=yes |
|---|
| asick7x | mp31 | Slow baby growth during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| asick8x | mp32 | Waters breaking early during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| aslpmore | dd29 | Does one twin sleep more than other (1st
Contact), see value labels | item | integer | nominal |
0=no, 1=yes elder
sleeps more, 2=yes younger sleeps more |
|---|
| aslpreg1/2 | dd28 | Does twin have regular sleeping pattern (1st
Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| aslpwake | dd30 | One twin crying wakes the other up (1st
Contact), see value labels | item | integer | ordinal |
0=no, 1=sometimes, 2=yes |
|---|
| asmoke | mp08 | Smoked cigarettes while pregnant (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asmoke1x | mp09 | Smoked cigarettes first three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asmoke2x | mp10 | Smoked cigarettes middle three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asmoke3x | mp11 | Smoked cigarettes last three months (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| asmokenu | mp12 | Number of cigarettes smoked per day while
pregant (1st Contact), see value labels | item | integer | ordinal |
0=0, 1=1-4, 2=5-9, 3=10-14, 4=15-19, 5=20 or more |
|---|
| aspcard1/2 | mp55, mp56, mp58, mp59 |
Twin had special care when born (1st Contact), see value labels |
item | integer | ordinal | 0=no, 1=1-2 days, 2=3-14 days,
3=15-30 days, 4=31-97 days, 5=98 or more days |
|---|
| aspcarc | mp57code | Reason for special care when born, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=premature, 2=jaundice/blood, 3=internal organs, 4=feeding/breathing, 5=unspecific response |
|---|
| astress | mp20 | Severe stress during pregnancy (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| astressc | mp21code | Cause of stress during pregnancy, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=bereavement, 2=financial or work problems, 3=moved or home problems,
4=marital or family problems, 5=personal illness or pregnancy problems |
|---|
| atempzyg | - | Zygosity difference scale (1st Contact), 0-1 |
derived | decimal | scale value | 0 to 1 |
|---|
| atwclub | dd01 | Member of a Twins Club (1st Contact), 1Y 0N |
item | integer | nominal | 0=no, 1=yes |
|---|
| atwinage | - | Age in years of twins at time of 1st Contact |
derived | decimal | quantitative | 1 to 18 (years) |
|---|
| atwmed1/2 | - | Twin medical risk factor composite scale
(1st Contact), standardised | derived | decimal | scale
value | approx. -2 to +4 (standardised) |
|---|
| avispro1/2 | mp74 | Twin has vision problems (1st Contact),
1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| avisproc | mp75code | Type of vision problem, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=squint, 2=eyesight, 3=physical eye defect |
|---|
| awork | dd37 | Respondent started work since twin birth (1st
Contact), see value labels | item | integer | nominal |
0=no, 1=yes full-time, 2=yes part-time |
|---|
| aworkdd | dd38 | Twin age when respondent
started work (1st Contact), see value labels | item | integer |
ordinal | 1=1-89 days (under 3 months), 2=90-149 days (3-5 months),
3=150-209 days (5-7 months), 4=210-360 days (7-12 months), 5=360-540 days (12-18 months),
6=541+ days (over 18 months) |
|---|
| azyblood | in17 | Do you know twin blood groups (1st
Contact), 1Y 0N | item | integer | nominal | 0=no,
1=yes |
|---|
| azyears | in11 | Differences in shape of twins ear lobes
(1st Contact), see value labels | item | integer | ordinal |
1=none, 2=slight, 3=clear difference |
|---|
| azyeyes | in09 | Differences in colour of twins eyes (1st
Contact), see value labels | item | integer | ordinal |
1=none, 2=slight, 3=clear difference |
|---|
| azyfac | - | Twins have different blood rhesus factors (1st
Contact), 1Y 0N | derived | integer | ordinal |
0=same, 1=different |
|---|
| azygrow | in24 | Change in likeness as twins grew older (1st
Contact), see value labels | item | integer | nominal |
1=same, 2=less, 3=more |
|---|
| azyhairs | in05 | Differences in shade of twins hair (1st
Contact), see value labels | item | integer | ordinal |
1=none, 2=slight, 3=clear difference |
|---|
| azyhairt | in07 | Differences in texture of twins hair (1st
Contact), see value labels | item | integer | ordinal |
1=none, 2=slight, 3=clear difference |
|---|
| azymistb | in31 | Babysitter/carer mistakes twins (1st
Contact), see value labels | item | integer | ordinal |
1=often, 2=sometimes, 3=rarely |
|---|
| azymistc | in33 | Casual friends mistake twins (1st
Contact), see value labels | item | integer | ordinal |
1=often, 2=sometimes, 3=rarely |
|---|
| azymistf | in32 | Close friends mistake twins (1st Contact),
see value labels | item | integer | ordinal |
1=often, 2=sometimes, 3=rarely |
|---|
| azymistm | in34 | Strangers mistake twins (1st Contact), see
value labels | item | integer | ordinal | 1=often,
2=sometimes, 3=rarely |
|---|
| azymistp | in28 | Other parent mistakes twins (1st Contact),
see value labels | item | integer | ordinal |
1=often, 2=sometimes, 3=rarely |
|---|
| azymistr | in30 | Relatives mistake twins (1st Contact), see
value labels | item | integer | ordinal | 1=often,
2=sometimes, 3=rarely |
|---|
| azymists | in29 | Older sibs mistake twins (1st Contact),
see value labels | item | integer | ordinal |
1=often, 2=sometimes, 3=rarely |
|---|
| azyold | in24 | Difference in likeness as twins grew older
(1st Contact), see value labels | item | integer | ordinal |
1=more, 2=same, 3=less |
|---|
| azypeas | in36 | Respondent opinion of twins likeness (1st
Contact), see value labels | item | integer | ordinal |
1=alike as peas in a pod, 2=alike as siblings, 3=not much alike |
|---|
| azyphotr | in27 | Can you tell twins apart from photos (1st
Contact), see value labels | item | integer | ordinal |
1=no, 2=hard, 3=easy |
|---|
| azyphoto | in27 | Can you tell twins apart from photos (1st
Contact), see value labels | item | integer | nominal |
0=no, 1=yes easily, 2=yes hard |
|---|
| azyphysi | in15 | Internal physical differences between
twins (1st Contact), 1Y 0N | item | integer | nominal |
0=no, 1=yes |
|---|
| azyprobs | in22 | Differences due to problems at birth (1st
Contact), see value labels | item | integer | nominal |
0=there are no differences, 1=no, 2=yes |
|---|
| azyprof | in01 | Zygosity from health professional (1st
Contact), 1MZ 2DZ | item | integer | ordinal | 1=identical, 2=non-identical |
|---|
| azyprofc | in02code | Reason for professional view of zygosity, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=one placenta or sac, 2=two placentas or sacs, 3=blood or DNA test,
4=unspecific mention of placenta, 5=IVF or known number of eggs,
6=view based on physical features, 7=unspecific response |
|---|
| azyteetr | in13 | Twins got same teeth within days, 1Y 2N |
item | integer | ordinal | 1=yes, 2=no |
|---|
| azyteeth | in13 | Did twins teeth appear at some time (1st
Contact), see value labels | item | integer | nominal |
1=yes matching same side, 2=yes matching opposite sides, 3=yes different
teeth, 4=no, 5=teeth not yet come through |
|---|
| azytoget | in35 | Are twins mistaken when together (1st
Contact), see value labels | item | integer | ordinal |
1=yes often, 2=yes sometimes, 3=almost never, 4=no |
|---|
| azytyp | - | Twins have different blood groups (1st
Contact), 1Y 0N | derived | integer | ordinal |
0=same, 1=different |
|---|
| azyyou | in03 | Respondent opinion of zygosity (1st
Contact), 1MZ 2DZ | item | integer | ordinal |
1=identical, 2=non-identical |
|---|
| azyyouc | in04code | Reason for respondent view of zygosity, coded from text (1st Contact), see value labels
| item | integer | nominal | 0=there was a text response but it was not entered,
1=physical similarity, 2=physical difference, 3=restatement of health professional reason |
|---|