Month of data collection
1 = January
2 = February
3 = March
4 = April
5 = May
6 = June
7 = July
8 = August
9 = September
10 = October
11 = November
12 = December

1 = PublicSchool
2 = PrivateSchool

1 = Urban
2 = Rural

1 = Country specific grade (11-year-old)
2 = Country specific grade (13-year-old)
3 = Country specific grade (15-year-old)

Boy or Girl (Binary Gender)
1 = Boy
2 = Girl

Self-rated health
1 = Excellent
2 = Good
3 = Fair
4 = Poor

Life satisfaction (Cantril ladder)
0 = 0 Worst possible life
1 = 1
2 = 2
3 = 3
4 = 4
5 = 5
6 = 6
7 = 7
8 = 8
9 = 9
10 = 10 Best possible life

Health complaints: Headache
1 = About every day
2 = More than once a week
3 = About every week
4 = About every month
5 = Rarely or never

Days with 60 min physical activity past 7 days (MVPA)
0 = 0 Days
1 = 1 Day
2 = 2 Days
3 = 3 Days
4 = 4 Days
5 = 5 Days
6 = 6 Days
7 = 7 Days

Think about body
1 = Much too thin
2 = A bit too thin
3 = About right
4 = A bit too fat
5 = Much too fat

Eating breakfast weekdays
1 = Never
2 = One day
3 = Two days
4 = Three days
5 = Four days
6 = Five days

Eating breakfast weekends
1 = Never
2 = One day
3 = Both days

Food consumption frequency: Eat fruits
1 = Never
2 = Less than once a week
3 = Once a week
4 = 2-4 days a week
5 = 5-6 days a week
6 = Once daily
7 = More than once daily

Family meals together
1 = Every day
2 = Most days
3 = About once a week
4 = Less often
5 = Never

Tooth brushing frequency
1 = More than once a day
2 = Once a day
3 = At least once a week
4 = Less than weekly
5 = Never

Vigorous physical activity (VPA): How often exercise
1 = Every day
2 = 4-6 times a week
3 = 3 times a week
4 = 2 times a week
5 = Once a week
6 = Once a month
7 = Less than once a month
8 = Never

I have felt cheerful and in good spirits
0 = At no time
1 = Some of the time
2 = Less than half of the time
3 = More than half of the time
4 = Most of the time
5 = All the time

Felt lonely past 12 months
1 = Never
2 = Rarely
3 = Sometimes
4 = Most of the time
5 = Always

Felt unable to control important things in life
1 = Never
2 = Almost never
3 = Sometimes
4 = Fairly often
5 = Very often

Times injured last 12 months
1 = None
2 = 1 time
3 = 2 times
4 = 3 times
5 = 4 times or more

Days drunk alcohol in lifetime
-99 = Inconsistent
1 = Never
2 = 1-2 days
3 = 3-5 days
4 = 6-9 days
5 = 10-19 days
6 = 20-29 days
7 = 30 days (or more)

Days drunk alcohol last 30 days
1 = Never
2 = 1-2 days
3 = 3-5 days
4 = 6-9 days
5 = 10-19 days
6 = 20-29 days
7 = 30 days (or more)

Drunkenness lifetime
-99 = Inconsistent
1 = No, never
2 = Yes, once
3 = Yes, 2-3 times
4 = Yes, 4-10 times
5 = Yes, more than 10 times

Drunkenness last 30 days
1 = No, never
2 = Yes, once
3 = Yes, 2-3 times
4 = Yes, 4-10 times
5 = Yes, more than 10 times

Days smoked e-cigarettes in lifetime
-99 = Inconsistent
1 = Never
2 = 1-2 days
3 = 3-5 days
4 = 6-9 days
5 = 10-19 days
6 = 20-29 days
7 = 30 days or more

Days smoked e-cigarettes last 30 days
1 = Never
2 = 1-2 days
3 = 3-5 days
4 = 6-9 days
5 = 10-19 days
6 = 20-29 days
7 = 30 days or more

School engagement, liking school
1 = Like a lot
2 = Like a bit
3 = Not very much
4 = Not at all

Pressured by schoolwork
1 = Not at all
2 = A little
3 = Some
4 = A lot

Students enjoy being together
1 = Strongly agree
2 = Agree
3 = Neither/nor
4 = Disagree
5 = Strongly disagree

Bullying perpetration (bullying others)
1 = Haven’t
2 = Once or twice
3 = 2-3 times per month
4 = Once a week
5 = Several times a week

Mother in main home
1 = Yes

Family car
1 = No
2 = Yes, one
3 = Yes, two or more

Own bedroom
1 = No
2 = Yes

No. of computers
1 = None
2 = One
3 = Two
4 = More than two

Family holidays
1 = Not at all
2 = Once
3 = Twice
4 = More than twice

Country of birth - ISO 3166
GB = United Kingdom of Great Britain and Northern Ireland
SH = Saint Helena, Ascension and Tristan da Cunha
MK = Macedonia (the former Yugoslav Republic of)
KP = Korea (the Democratic People's Republic of)
GS = South Georgia and the South Sandwich Islands

Father job
1 = Yes
2 = No
3 = Don’t know
4 = Don’t know or see

Father, reason not job
1 = Sick/ retired/ stud.
2 = Looking for work
3 = Care/ home
4 = Don’t know

Talk to father
1 = Very easy
2 = Easy
3 = Difficult
4 = Very difficult
5 = Don’t have or see

Family tries to help
1 = Very strongly disagree
2 = 2
3 = 3
4 = 4
5 = 5
6 = 6
7 = Very strongly agree

Onl contact close friends
1 = Don’t know/NA
2 = Never/almost never
3 = At least every week
4 = Daily
5 = Several times daily
6 = Almost all the time

Sexual intercourse
1 = Yes
2 = No

Age when first sexual intercourse
1 = 11 years or younger
2 = 12 years
3 = 13 years
4 = 14 years
5 = 15 years
6 = 16 years and older

Contraceptive last intercourse: Condom
1 = Yes
2 = No
3 = Don't know

Number of days gaming a week
1 = (Almost) never
2 = Less than one day a week
3 = 1 day a week
4 = 2 or 3 days a week
5 = 4 or 5 days a week
6 = (Almost) every day

Number of hours gaming a day
1 = 1 to 2 hours
2 = 2 to 4 hours
3 = 4 to 6 hours
4 = 6 to 8 hours
5 = 8 hours or more

All that you could think of was gaming
0 = No
1 = Yes

Feelings, more easily online
1 = Strongly disagree
2 = Disagree
3 = Neither agree nor disagree
4 = Agree
5 = Strongly agree

Feeling nervous, anxious or on edge
0 = Not at all
1 = Several days
2 = More than half of the days
3 = Nearly every day

Future chances of: Being involved in helping other people
1 = Very low
2 = Low
3 = About 50/50
4 = High
5 = Very high

Amount of time sitting during free time
1 = Almost no time
2 = A little time
3 = Moderate amount of time
4 = A lot of time
5 = Almost all the time

Playing games on an electronic device
1 = None at all
2 = About half an hour a day
3 = About 1 hour a day
4 = About 2 hours a day
5 = About 3 hours a day
6 = About 4 hours a day
7 = About 5 hours a day
8 = About 6 hours a day
9 = About 7 or more hours a day

Called names
1 = I have not been bullied in this way in the past couple of months
2 = Once or twice
3 = 2 or 3 times a month
4 = About once a week
5 = Several times a week

Called another student mean names
1 = Not bullied others in this way in the past couple of months
2 = Once or twice
3 = 2 or 3 times a month
4 = About once a week
5 = Several times a week

Tested positive for COVID-19
1 = Yes
2 = No
3 = I do not know

Impact COVID-19 on life as whole
1 = Very negative
2 = Quite negative
3 = Neither positive nor negative
4 = Quite positive
5 = Very positive

COVID-19 info from family
1 = Never
2 = Rarely
3 = Sometimes
4 = Often
5 = Always

Mode of questionnaire administration
1 = ‘Pen and paper’ 2 ‘Computer’

Missing birthmonth is set to June
1 = Estimated for this respondent

Body Mass Index
0 = Outside overall range

1 = 11-y-o
2 = 13-y-o
3 = 15-y-o