Internal consistency of study scales and subscales by survey mode_
| Scale | Number of items | Internal consistency (α) | |
|---|---|---|---|
| Electronic mode | Paper mode | ||
| HBSC symptom checklist | 8 | .78 | .79 |
| Family Affluence Scale | 6 | .52 | .58 |
| Multidimensional Scale of Perceived Social Support: Family | 4 | .76 | .69 |
| Multidimensional Scale of Perceived Social Support: Friends | 4 | .90 | .85 |
| Teacher and Classmate Support Scale: Classmates | 3 | .77 | .70 |
| Teacher and Classmate Support Scale: Teachers | 3 | .75 | .74 |
| Online contact with friends and others | 4 | .54 | .54 |
| Preference for online communication | 3 | .84 | .81 |
| Social media addiction | 9 | .75 | .76 |
Health behaviours of schoolchildren by survey mode_
| Characteristic | Prevalence, % | % difference | OR | P | ||
|---|---|---|---|---|---|---|
| Electronic | Paper | |||||
| Eating habits | ||||||
| Having breakfast during the weekdays | Every day | 58.8 | 62.7 | 3.9 | 1.18 | .366 |
| Having breakfast during the weekends | Every day | 79.6 | 87.7 | 8.1 | 1.93 | .009 |
| Having breakfast with parents | Every day | 41.0 | 40.7 | -.3 | 1.00 | .982 |
| Having dinner with parents | Every day | 47.1 | 45.6 | -1.5 | .96 | .816 |
| Eating fruits | Every day | 41.8 | 38.5 | -3.3 | .87 | .446 |
| Eating vegetables | Every day | 32.6 | 34.2 | 1.6 | 1.07 | .707 |
| Eating sweets | Every day | 16.1 | 13.8 | -2.3 | .83 | .453 |
| Drinking soft drinks | Every day | 5.4 | 6.3 | .9 | 1.23 | .593 |
| Drinking energy drinks | Every day | 2.3 | .4 | -1.9 | .16 | .097 |
| Health and well-being | ||||||
| Subjective health assessment | Good | 88.5 | 91.8 | 3.3 | 1.59 | .132 |
| Life satisfaction | 6–10 (10 pts scale) | 87.7 | 85.8 | -1.9 | .84 | .510 |
| Headache | Rarely | 84.3 | 82.5 | -1.8 | .91 | .707 |
| Stomach ache | Rarely | 93.5 | 93.7 | .2 | 1.04 | .912 |
| Backache | Rarely | 91.6 | 92.1 | .5 | 1.09 | .794 |
| Feeling low | Rarely | 80.1 | 81.3 | 1.2 | 1.14 | .577 |
| Irritability or bad temper | Rarely | 72.0 | 76.5 | 4.5 | 1.39 | .115 |
| Feeling nervous | Rarely | 70.5 | 69.7 | -.8 | 1.01 | .946 |
| Difficulties in getting to sleep | Rarely | 79.7 | 83.2 | 3.5 | 1.33 | .214 |
| Feeling dizzy | Rarely | 89.7 | 89.9 | .2 | 1.08 | .798 |
| Brushing the teeth | More than once a day | 61.3 | 62.8 | 1.5 | 1.05 | .809 |
| Body image | A bit too thin | 11.9 | 15.0 | 3.1 | .71 | .200 |
| A bit too fat | 29.1 | 30.7 | 1.6 | .91 | .654 | |
| About the right size | 59.0 | 54.3 | -4.7 | 1.00 | - | |
| Physical activity | ||||||
| Physical activity at least 60 minutes per day (last week) | 7 days | 18.9 | 20.6 | 1.7 | 1.16 | .518 |
| Exercise in free time until getting out of breath or sweating | Every day | 3.1 | 19.7 | 16.6 | 8.08 | <.001 |
| Risk behaviour | ||||||
| Cigarette smoking (lifetime) | Never | 73.2 | 77.8 | 4.6 | 1.37 | .187 |
| Cigarette smoking (last month) | Never | 88.1 | 92.3 | 4.2 | 1.75 | .097 |
| Alcohol drinking (lifetime) | Never | 62.8 | 68.4 | 5.6 | 1.37 | .129 |
| Alcohol drinking (last month) | Never | 88.9 | 88.0 | -.9 | .89 | .706 |
| Cannabis taking (lifetime) | Never | 94.3 | 97.0 | 2.7 | 2.22 | .101 |
| Cannabis taking (last month) | Never | 98.1 | 99.2 | 1.1 | 2.13 | .376 |
| Sexual intercourse | No | 95.0 | 93.3 | -1.7 | .81 | .626 |
Family-related perceptions of schoolchildren by survey mode_
| Characteristic | Prevalence, % | % difference | OR | P | ||
|---|---|---|---|---|---|---|
| Electronic | Paper | |||||
| Communication | ||||||
| Ease to talk about things that really bother: to father | Easy | 63.2 | 69.7 | 6.5 | 1.43 | .068 |
| Ease to talk about things that really bother: to stepfather | Easy | 11.5 | 15.5 | 4.0 | 1.48 | .221 |
| Ease to talk about things that really bother: to mother | Easy | 79.7 | 82.0 | 2.3 | 1.15 | .526 |
| Ease to talk about things that really bother: to stepmother | Easy | 9.6 | 10.1 | .5 | 1.08 | .848 |
| Support | ||||||
| Family really tries helping | Agree | 92.0 | 93.7 | 1.7 | 1.29 | .461 |
| Getting emotional help and support from family | Agree | 83.9 | 88.0 | 4.1 | 1.43 | .164 |
| Being able to talk about problems with family | Agree | 69.3 | 71.2 | 1.9 | 1.13 | .537 |
| Family is willing to help in making decisions | Agree | 86.6 | 90.3 | 3.7 | 1.45 | .183 |
| Affluence | ||||||
| Own bedroom | Yes | 81.2 | 81.4 | .2 | 1.02 | .941 |
| Dishwasher at home | Yes | 62.5 | 59.7 | -2.8 | .87 | .496 |
| Bathrooms at home | One or more | 97.7 | 97.8 | .1 | 1.03 | .958 |
| Family car | One or more | 95.0 | 93.7 | -1.3 | .78 | .525 |
| Computers at home | One or more | 97.3 | 97.7 | .4 | 1.15 | .806 |
| Family travel abroad for vacation, last year | Once or more | 86.5 | 81.6 | -4.9 | .68 | .129 |
Electronic media communication of schoolchildren by survey mode_
| Characteristic | Prevalence, % | % difference | OR | P | ||
|---|---|---|---|---|---|---|
| Electronic | Paper | |||||
| Online contact with friends and others | ||||||
| Close friend(s) | Every day | 66.7 | 63.3 | -3.4 | .81 | .277 |
| Friends from a larger friend group | Every day | 37.9 | 40.6 | 2.7 | .12 | .535 |
| Friends that you got to know through the internet but didn’t know before | Every day | 11.5 | 14.7 | 3.2 | 1.32 | .302 |
| Other people than friends | Every day | 44.8 | 47.7 | 2.9 | 1.11 | .563 |
| Preference for online communication | ||||||
| On the internet, I talk more easily about secrets than in a face-to-face encounter | Agree | 27.3 | 25.7 | -1.6 | .93 | .725 |
| On the internet, I talk more easily about my inner feelings than in a face-to-face encounter | Agree | 26.8 | 22.4 | -4.4 | .78 | .238 |
| On the internet, I talk more easily about my concerns than in a face-to-face encounter | Agree | 27.6 | 20.1 | -7.5 | .67 | .054 |
| Social media addiction | ||||||
| Regularly felt dissatisfied because you wanted to spend more time on social media | Yes | 16.9 | 18.0 | 1.1 | 1.03 | .912 |
| Often felt bad when you could not use social media | Yes | 27.2 | 25.7 | -1.5 | .88 | .528 |
| Tried to spend less time on social media, but failed | Yes | 28.7 | 25.3 | -3.4 | .81 | .284 |
| Regularly neglected other activities (e.g. hobbies, sport) because you wanted to use social media | Yes | 13.8 | 12.4 | -1.4 | .90 | .700 |
| Regularly had arguments with others because of your social media use | Yes | 14.9 | 12.0 | -2.9 | .76 | .290 |
| Regularly lied to your parents or friends about the amount of time you spend on social media | Yes | 17.2 | 16.1 | -1.1 | .89 | .628 |
| Often used social media to escape from negative feelings | Yes | 30.3 | 22.5 | -7.8 | .64 | .030 |
| Had serious conflict with your parents, brother(s) or sister(s) because of your social media use | Yes | 21.8 | 13.5 | -8.3 | .49 | .004 |
| Regularly found that you can’t think of anything else but the moment that you will be able to use social media again | Yes | 40.6 | 39.9 | -.7 | .93 | .704 |
School behaviours of schoolchildren by survey mode_
| Characteristic | Prevalence, % | % difference | OR | P | ||
|---|---|---|---|---|---|---|
| Electronic | Paper | |||||
| Friends support | ||||||
| Friends help | Agree | 76.6 | 76.4 | -.2 | .97 | .870 |
| Counting on friends | Agree | 75.1 | 78.3 | 3.2 | 1.18 | .440 |
| Having friends to share joys and sorrows | Agree | 78.2 | 87.7 | 9.5 | 1.98 | .005 |
| Being able to talk about problems with friends | Agree | 70.5 | 76.4 | 5.9 | 1.35 | .138 |
| Classmate support | ||||||
| Enjoy being together with students | Agree | 59.8 | 54.1 | -5.7 | .81 | .243 |
| Students in class are kind and helpful | Agree | 53.3 | 52.8 | -.5 | 1.00 | .982 |
| Students accepting one as he/she is | Agree | 67.4 | 61.8 | -5.6 | .80 | .231 |
| Teacher support | ||||||
| Teachers accepting one as he/she is | Agree | 75.1 | 78.1 | 3.0 | 1.23 | .348 |
| Teachers caring | Agree | 49.8 | 52.6 | 2.8 | 1.15 | .426 |
| Feeling a lot of trust in teachers | Agree | 65.1 | 67.5 | 2.4 | 1.16 | .462 |
| School perception | ||||||
| Feeling about school | I like it a lot | 81.1 | 82.9 | 1.8 | 1.14 | .586 |
| Pressure by schoolwork | Some or a lot | 72.2 | 72.7 | .5 | .99 | .947 |
| Bullying | ||||||
| Taking part in bullying another student | Yes | 44.2 | 42.9 | -1.3 | .97 | .889 |
| at school, last two months | ||||||
| Being bullied at school, last two months | Yes | 50.2 | 46.5 | -3.7 | .86 | .402 |
| Taking part in cyber-bullying, last two months | Yes | 20.3 | 18.7 | -1.6 | .92 | .708 |
| Being cyber-bullied, last two months | Yes | 14.1 | 22.3 | 8.2 | 1.82 | .011 |
| Physical fighting | ||||||
| Having a physical fight, last year | Yes | 31.7 | 29.4 | -2.3 | .92 | .688 |
| Injuries | ||||||
| Being injured with treatment needed, last year | Yes | 48.8 | 57.6 | 8.8 | 1.45 | .036 |
The main characteristics of study sample_
| Characteristic | Electronic mode | Paper mode | n | Response rate |
|---|---|---|---|---|
| Gender | ||||
| Boys | 51.4 | 48.6 | 255 | 77.0 |
| Girls | 47.3 | 52.7 | 275 | 89.0 |
| Grade | ||||
| 5th | 49.7 | 50.3 | 187 | 77.9 |
| 7th | 48.8 | 51.2 | 201 | 84.1 |
| 9th | 49.0 | 51.0 | 143 | 88.8 |
| School | ||||
| #1 (large city) | 47.3 | 52.7 | 74 | 89.2 |
| #2 (large city) | 48.7 | 51.3 | 224 | 94.5 |
| #3 (city) | 50.5 | 49.5 | 103 | 60.6 |
| #4 (city) | 50.0 | 50.0 | 48 | 80.0 |
| #5 (town) | 50.0 | 50.0 | 82 | 91.1 |