TEDS Data Dictionary

Variables in the 8 Year Dataset

The table on this page lists all 8 Year variables. This includes all item variables from the 8 Year questionnaire, as well as derived variables that are based on 8 Year items.

The table does not include background variables that originate from other sources (either from admin data or from other study datasets). Such variables include IDs, twin sex and zygosity variables, the random variable and general exclusion variables. See the background variables page for details.

Variables are listed in alphabetical order in the table below. The columns of the table are:

Dataset variable name.
Item or derived variable?
- item variables are shown in an annotated questionnaire (pdf); derived variables are described in detail on another page.
Dataset variable label
Data type:
- integer - numeric whole numbers
- decimal - numeric with fractional values
Variable type:
- nominal - categorical, with arbitrary numeric values
- ordinal - categorical, with ordered numeric values
- quantitative - numerical measurements of some concrete quantity
- scale value - numerical measurement derived (usually) as a sum or mean of other variables
Coding or range of values - this shows the value coding used for nominal/ordinal variables, or an approximate range of values for quantitative and scale variables.

dataset variable name	item or derived variable?	dataset variable label	data type	variable type	coding or approximate range of values
hage	derived	Age of twins when 8yr questionnaire completed (or returned)	decimal	quantitative	6.85 to 9.5 (age in years)
hbirtord	item	Incorrect birth order in 8yr questionnaire, 1Y	integer	nominal	0=no, 1=yes
hca011/2	item	Cast at 8: join in games with other children, 1Y 0N	integer	nominal	0=no, 1=yes
hca01r1/2	item	Cast at 8: join in games with other children (reversed)	integer	nominal	0=yes, 1=no
hca021/2	item	Cast at 8: spontaneously comes to chat, 1Y 0N	integer	nominal	0=no, 1=yes
hca02r1/2	item	Cast at 8: spontaneously comes to chat (reversed)	integer	nominal	0=yes, 1=no
hca031/2	item	Cast (control Q) at 8: was speaking by age two, 1Y 0N	integer	nominal	0=no, 1=yes
hca03r1/2	item	Cast (control Q) at 8: was speaking by age two (reversed)	integer	nominal	0=yes, 1=no
hca041/2	item	Cast (control Q) at 8: enjoy sports, 1Y 0N	integer	nominal	0=no, 1=yes
hca04r1/2	item	Cast (control Q) at 8: enjoy sports (reversed)	integer	nominal	0=yes, 1=no
hca051/2	item	Cast at 8: important to fit in with peers, 1Y 0N	integer	nominal	0=no, 1=yes
hca05r1/2	item	Cast at 8: important to fit in with peers (reversed)	integer	nominal	0=yes, 1=no
hca061/2	item	Cast at 8: notice unusual details, 1Y 0N	integer	nominal	0=no, 1=yes
hca06r1/2	item	Cast at 8: notice unusual details (reversed)	integer	nominal	0=yes, 1=no
hca071/2	item	Cast at 8: take things literally, 1Y 0N	integer	nominal	0=no, 1=yes
hca07r1/2	item	Cast at 8: take things literally (reversed)	integer	nominal	0=yes, 1=no
hca081/2	item	Cast at 8: lot of time pretending when age three, 1Y 0N	integer	nominal	0=no, 1=yes
hca08r1/2	item	Cast at 8: lot of time pretending when age three (reversed)	integer	nominal	0=yes, 1=no
hca091/2	item	Cast at 8: do things over and over, 1Y 0N	integer	nominal	0=no, 1=yes
hca09r1/2	item	Cast at 8: do things over and over (reversed)	integer	nominal	0=yes, 1=no
hca101/2	item	Cast at 8: easy to interact with other children, 1Y 0N	integer	nominal	0=no, 1=yes
hca10r1/2	item	Cast at 8: easy to interact with other children (reversed)	integer	nominal	0=yes, 1=no
hca111/2	item	Cast at 8: keep a two-way conversation going, 1Y 0N	integer	nominal	0=no, 1=yes
hca11r1/2	item	Cast at 8: keep a two-way conversation going (reversed)	integer	nominal	0=yes, 1=no
hca121/2	item	Cast (control Q) at 8: read appropriately for age, 1Y 0N	integer	nominal	0=no, 1=yes
hca12r1/2	item	Cast (control Q) at 8: read appropriately for age (reversed)	integer	nominal	0=yes, 1=no
hca131/2	item	Cast at 8: same interests as peers, 1Y 0N	integer	nominal	0=no, 1=yes
hca13r1/2	item	Cast at 8: same interests as peers (reversed)	integer	nominal	0=yes, 1=no
hca141/2	item	Cast at 8: interest takes up so much time, 1Y 0N	integer	nominal	0=no, 1=yes
hca14r1/2	item	Cast at 8: interest takes up so much time (reversed)	integer	nominal	0=yes, 1=no
hca151/2	item	Cast at 8: friends not just acquaintances, 1Y 0N	integer	nominal	0=no, 1=yes
hca15r1/2	item	Cast at 8: friends not just acquaintances (reversed)	integer	nominal	0=yes, 1=no
hca161/2	item	Cast at 8: brings things interested in, 1Y 0N	integer	nominal	0=no, 1=yes
hca16r1/2	item	Cast at 8: brings things interested in (reversed)	integer	nominal	0=yes, 1=no
hca171/2	item	Cast at 8: enjoy joking around, 1Y 0N	integer	nominal	0=no, 1=yes
hca17r1/2	item	Cast at 8: enjoy joking around (reversed)	integer	nominal	0=yes, 1=no
hca181/2	item	Cast at 8: difficulty with rules for polite behaviour, 1Y 0N	integer	nominal	0=no, 1=yes
hca18r1/2	item	Cast at 8: difficulty with rules for polite behaviour (reversed)	integer	nominal	0=yes, 1=no
hca191/2	item	Cast at 8: unusual memory for details, 1Y 0N	integer	nominal	0=no, 1=yes
hca19r1/2	item	Cast at 8: unusual memory for details (reversed)	integer	nominal	0=yes, 1=no
hca201/2	item	Cast at 8: unusual voice, 1Y 0N	integer	nominal	0=no, 1=yes
hca20r1/2	item	Cast at 8: unusual voice (reversed)	integer	nominal	0=yes, 1=no
hca211/2	item	Cast at 8: people important, 1Y 0N	integer	nominal	0=no, 1=yes
hca21r1/2	item	Cast at 8: people important (reversed)	integer	nominal	0=yes, 1=no
hca221/2	item	Cast (control Q) at 8: can dress self, 1Y 0N	integer	nominal	0=no, 1=yes
hca22r1/2	item	Cast (control Q) at 8: can dress self (reversed)	integer	nominal	0=yes, 1=no
hca231/2	item	Cast at 8: good at turn-taking in conversation, 1Y 0N	integer	nominal	0=no, 1=yes
hca23r1/2	item	Cast at 8: good at turn-taking in conversation (reversed)	integer	nominal	0=yes, 1=no
hca241/2	item	Cast at 8: play imaginatively, 1Y 0N	integer	nominal	0=no, 1=yes
hca24r1/2	item	Cast at 8: play imaginatively (reversed)	integer	nominal	0=yes, 1=no
hca251/2	item	Cast at 8: tactless or socially inappropriate, 1Y 0N	integer	nominal	0=no, 1=yes
hca25r1/2	item	Cast at 8: tactless or socially inappropriate (reversed)	integer	nominal	0=yes, 1=no
hca261/2	item	Cast (control Q) at 8: can count to 50, 1Y 0N	integer	nominal	0=no, 1=yes
hca26r1/2	item	Cast (control Q) at 8: can count to 50 (reversed)	integer	nominal	0=yes, 1=no
hca271/2	item	Cast at 8: make normal eye contact, 1Y 0N	integer	nominal	0=no, 1=yes
hca27r1/2	item	Cast at 8: make normal eye contact (reversed)	integer	nominal	0=yes, 1=no
hca281/2	item	Cast at 8: unusual/repetitive movements, 1Y 0N	integer	nominal	0=no, 1=yes
hca28r1/2	item	Cast at 8: unusual/repetitive movements (reversed)	integer	nominal	0=yes, 1=no
hca291/2	item	Cast at 8: one-sided social behaviour, 1Y 0N	integer	nominal	0=no, 1=yes
hca29r1/2	item	Cast at 8: one-sided social behaviour (reversed)	integer	nominal	0=yes, 1=no
hca301/2	item	Cast at 8: says you or s/he instead of I, 1Y 0N	integer	nominal	0=no, 1=yes
hca30r1/2	item	Cast at 8: says you or s/he instead of I (reversed)	integer	nominal	0=yes, 1=no
hca311/2	item	Cast at 8: prefers imaginative activities, 1Y 0N	integer	nominal	0=no, 1=yes
hca31r1/2	item	Cast at 8: prefers imaginative activities (reversed)	integer	nominal	0=yes, 1=no
hca321/2	item	Cast at 8: sometimes loses listener, 1Y 0N	integer	nominal	0=no, 1=yes
hca32r1/2	item	Cast at 8: sometimes loses listener (reversed)	integer	nominal	0=yes, 1=no
hca331/2	item	Cast (control Q) at 8: can ride bicycle, 1Y 0N	integer	nominal	0=no, 1=yes
hca33r1/2	item	Cast (control Q) at 8: can ride bicycle (reversed)	integer	nominal	0=yes, 1=no
hca341/2	item	Cast at 8: imposes routines, 1Y 0N	integer	nominal	0=no, 1=yes
hca34r1/2	item	Cast at 8: imposes routines (reversed)	integer	nominal	0=yes, 1=no
hca351/2	item	Cast at 8: cares how perceived by group, 1Y 0N	integer	nominal	0=no, 1=yes
hca35r1/2	item	Cast at 8: cares how perceived by group (reversed)	integer	nominal	0=yes, 1=no
hca361/2	item	Cast at 8: turns conversation to favourite subject, 1Y 0N	integer	nominal	0=no, 1=yes
hca36r1/2	item	Cast at 8: turns conversation to favourite subject (reversed)	integer	nominal	0=yes, 1=no
hca371/2	item	Cast at 8: has odd phrases, 1Y 0N	integer	nominal	0=no, 1=yes
hca37r1/2	item	Cast at 8: has odd phrases (reversed)	integer	nominal	0=yes, 1=no
hcacomt1/2	derived	Cast Communication Total scale at 8 (0-12)	decimal	scale value	0 to 12
hcanont1/2	derived	Cast Non-Social Total scale at 8 (0-7)	decimal	scale value	0 to 7
hcasoct1/2	derived	Cast Social Total scale at 8 (0-12)	decimal	scale value	0 to 12
hcastt1/2	derived	Cast overall Total scale at 8 (0-31)	decimal	scale value	0 to 31
hcon011/2	item	Conners ADHD at 8: always on the go, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon021/2	item	Conners ADHD at 8: avoids sustained mental effort, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon031/2	item	Conners ADHD at 8: difficulty sustaining attention, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon041/2	item	Conners ADHD at 8: does not seem to listen, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon051/2	item	Conners ADHD at 8: runs/climbs excessively, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon061/2	item	Conners ADHD at 8: fails to follow through or finish, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon071/2	item	Conners ADHD at 8: difficulty organising, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon081/2	item	Conners ADHD at 8: talks excessively, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon091/2	item	Conners ADHD at 8: makes careless mistakes, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon101/2	item	Conners ADHD at 8: difficulty waiting turn, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon111/2	item	Conners ADHD at 8: interrupts or intrudes, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon121/2	item	Conners ADHD at 8: forgetful, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon131/2	item	Conners ADHD at 8: fidgets or squirms, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon141/2	item	Conners ADHD at 8: difficulty playing quietly, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon151/2	item	Conners ADHD at 8: loses things, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon161/2	item	Conners ADHD at 8: leaves seat, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon171/2	item	Conners ADHD at 8: easily distracted, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hcon181/2	item	Conners ADHD at 8: blurts out answers, 0not at all .. 3very much true	integer	ordinal	0=not true at all, 1=just a little true, 2=pretty much true, 3=very much true
hconhit1/2	derived	Conners Hyperactivitiy-Impulsivity Total at 8 (0-27)	decimal	scale value	0 to 27
hconint1/2	derived	Conners Inattention Total at 8 (0-27)	decimal	scale value	0 to 27
hconnt1/2	derived	Conners ADHD overall Total at 8 (0-54)	decimal	scale value	0 to 54
hconsig	item	Signature giving consent on 8yr questionnaire, 1Y	integer	nominal	0=no, 1=yes
hdadhd1/2	item	Cast: ADHD/hyperactivity ever diagosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdaspg1/2	item	Cast: aspergers syndrome ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdauti1/2	item	Cast: autism ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hddown1/2	item	Cast: downs syndrome ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hddysl1/2	item	Cast: dyslexia ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdevcon1/2	item	Cast: teachers/health visitors ever had concerns about development at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdfrgx1/2	item	Cast: fragile X ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdhrvs1/2	item	Cast: hearing/visual difficulties ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdlngd1/2	item	Cast: language delay ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
hdtour1/2	item	Cast: tourettes syndrome ever diagnosed at 8, 1Y 0N	integer	nominal	0=no, 1=yes
heightyr	item	8yr data present, 1Y	integer	nominal	1=yes
hLLCage	derived	Age of twin when 8 year questionnaire completed (for use in LLC TRE), months	integer	quantitative	approx. 83 to 110 (months)
hLLCdate	derived	Date when 8 year questionnaire completed (for use in LLC TRE), yyyy-mm string	string	date value	approx. '2002-11' to '2004-07'
hrpq011/2	item	RPQ at 8: afraid of new situations, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq021/2	item	RPQ at 8: acts younger than age, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq031/2	item	RPQ at 8: gets too physically close, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq041/2	item	RPQ at 8: often unhappy, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq051/2	item	RPQ at 8: too cuddly, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq061/2	item	RPQ at 8: apathetic, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq071/2	item	RPQ at 8: asks personal questions, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq081/2	item	RPQ at 8: aggressive to self, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq091/2	item	RPQ at 8: has few friends, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq101/2	item	RPQ at 8: has no conscience, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq111/2	item	RPQ at 8: too friendly with strangers, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq121/2	item	RPQ at 8: very clingy, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq131/2	item	RPQ at 8: difficult to comfort, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq141/2	item	RPQ at 8: looks frozen with fear, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq151/2	item	RPQ at 8: attention seeking, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq161/2	item	RPQ at 8: runs away when approached, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq171/2	item	RPQ at 8: false affection, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpq181/2	item	RPQ at 8: unpredictable friendliness, 3definitely agree .. 0definitely disagree	integer	ordinal	3=definitely agree, 2=slightly agree, 1=slightly disagree, 0=definitely disagree
hrpqt1/2	derived	RPQ overall Total at 8 (0-54)	decimal	scale value	0 to 54
hs1art1/2	item	Striking skill in art/drawing for general ability level at 8, 1Y	integer	nominal	1=yes
hs1mat1/2	item	Striking skill in maths/calculation for general ability level at 8, 1Y	integer	nominal	1=yes
hs1mem1/2	item	Striking skill in memory for general ability level at 8, 1Y	integer	nominal	1=yes
hs1mus1/2	item	Striking skill in music for general ability level at 8, 1Y	integer	nominal	1=yes
hs1oth1/2	item	Striking skill in other area for general ability level at 8, 1Y	integer	nominal	1=yes
hs2art1/2	item	Striking skill in art/drawing for his/her age at 8, 1Y	integer	nominal	1=yes
hs2mat1/2	item	Striking skill in maths/calculation for his/her age at 8, 1Y	integer	nominal	1=yes
hs2mem1/2	item	Striking skill in memory for his/her age at 8, 1Y	integer	nominal	1=yes
hs2mus1/2	item	Striking skill in music for his/her age at 8, 1Y	integer	nominal	1=yes
hs2oth1/2	item	Striking skill in other area for his/her age at 8, 1Y	integer	nominal	1=yes
hs3art1/2	item	Special gift in art/drawing compared with older children at 8, 1Y	integer	nominal	1=yes
hs3mat1/2	item	Special gift in maths/calculation compared with older children at 8, 1Y	integer	nominal	1=yes
hs3mem1/2	item	Special gift in memory compared with older children at 8, 1Y	integer	nominal	1=yes
hs3mus1/2	item	Special gift in music compared with older children at 8, 1Y	integer	nominal	1=yes
hs3oth1/2	item	Special gift in other area compared with older children at 8, 1Y	integer	nominal	1=yes