Adolescent Smartphone Overdependence in South Korea: A Place-Stratified Evaluation of Conceptually Informed AI/ML Modeling
Abstract
1. Introduction
Research Aims and Contributions
- Develop a high-performing low-risk screening tool to detect adolescents at risk of smartphone overdependence using conceptually informed AI/ML modeling;
- Leverage AI/ML toward construct exploration of contributing factors;
- Provide place-based policy profiles that offer insights into local variations in risk factors and model performance, enabling targeted intervention.
2. Materials and Methods
2.1. Data
2.2. Outcome
2.3. Conceptual Feature Selection and Construct Grouping
- Intent to Seek Smartphone Education. This construct captures adolescents’ intention to engage in preventive education related to smartphone use [48]. Intention to seek smartphone education can be understood as a proxy within the broader help-seeking framework for behavioral addictions. Treatment- or help-seeking studies highlight its association with smartphone struggles across countries [48,49,50] and in other smartphone-accessible issues such as internet gaming disorder, internet addiction, and social network sites [51,52].
- Preventive Education. This reflects actual participation in any educational or intervention programs to prevent smartphone addiction [53,54]. Although evidence for their efficacy and effectiveness remains mixed [55,56,57,58], adolescents who have received such education often demonstrate greater awareness and are more likely to engage in help-seeking behaviors. Those who have received such education tend to have greater awareness of the risks, perceive the programs as more helpful when at high risk, and even demonstrate reduced overdependence and improved self-control in some cases [53,59,60].
- Smartphone Use Cases. This measures the frequency of engagement with different smartphone functions (e.g., gaming, video streaming, and navigation) [61]. Prior studies have found important associations between the types of smartphone use and overdependence across populations, including adolescents [34,62]. Entertainment and social networking applications, in particular, have been linked to increased overdependence due to their reward structures and habit-forming properties [63].
- Home Environment. The home environment includes both physical and psychological aspects of the household context [64]. Prior studies have shown that conditions such as socioeconomic status, family structure, and parental support can shape adolescent behavior and potentially influence smartphone use [65,66]. For instance, socioeconomic status is linked to adolescents’ screen media use [67].
- Parental Prevention Efforts. Parental prevention efforts refer to the strategies parents use to manage and guide their children’s media use, including rule-setting, supervision, and open dialogue [68,69,70]. Active parental prevention efforts have been found to reduce risk of smartphone addiction, while overly restrictive or absent parenting may increase it [71,72,73]. In addition, parental mediation and psychological control significantly predict problematic smartphone use through mechanisms such as psychological reactance and resilience [71,74,75].
- Perceived Digital Competence and Risk. This construct refers to individuals’ perceived abilities to effectively navigate digital environments (e.g., digital content creation and privacy awareness) as well as their perceived smartphone issues (e.g., excessive use and difficulty controlling short-form video consumption). These perceptions may shape how individuals engage with digital technology and manage potential overdependence [83]. Notably, from a cognitive–behavioral perspective, such self-evaluations can reflect cognitive distortions [84]. In the smartphone literature, maladaptive cognitions and impaired self-regulation reinforce problematic use [46,47]. In addition, Perceived Digital Competence has emerged as a relevant construct where prior research has demonstrated that higher digital literacy can buffer risks in some groups but also exacerbate overdependence when combined with stress or limited coping resources [85].
- Smartphone Consequences and Dependence. Smartphone Consequences and Dependence is characterized by emotional suffering, typically involving symptoms of depression and anxiety [19,90,91]. Excessive smartphone use has been linked to increased psychological distress and related cognitive and neurological effects [19,92].
2.4. Artificial Intelligence/Machine Learning Models
2.4.1. Conceptual Framework
2.4.2. AI/ML Classification Modeling
Data Processing
AI/ML Procedures
2.4.3. Explainable AI (XAI) Techniques
2.4.4. Place-Stratified Predictive Analysis
3. Results
3.1. Sample Descriptives
3.2. Overview of AI/ML Results
3.2.1. Performance Comparison for Nested AI/ML Classifiers
3.2.2. Performance Comparison Between Construct-Based AI/ML Classifiers
3.3. Four Exemplar Models
3.3.1. M4 (+Smartphone Use Cases) Nested Model
Feature Importance
Place-Stratified Results
Placed-Stratified Feature Importance
3.3.2. Smartphone Consequences and Dependence Classifier Results
Feature Importance
Place-Stratified Results
Placed-Stratified Feature Importance
3.3.3. Perceived Digital Competence and Risk Classifier Results
Feature Importance
Place-Stratified Results
Placed-Stratified Feature Importance
3.3.4. Smartphone Use Case Results
Feature Importance
Place-Stratified Results
Placed-Stratified Feature Importance
4. Discussion
4.1. Place-Based Policy Implication Profiles
4.1.1. Metropolitan Cities
4.1.2. Medium and Small Cities
4.1.3. Towns and Rural Districts
4.2. Limitations and Future Research
5. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Data Availability Statement
Conflicts of Interest
Appendix A. Conceptual Feature Selection and Construct Grouping
| Domains/Constructs | Features |
|---|---|
| Demographics | Male |
| Age | |
| Elementary School | |
| Middle School | |
| High School | |
| Urbanicity | Metropolitan City |
| Medium/Small City | |
| Town/Rural District | |
| Preventive Education Experiences | Smartphone Overdependence Prevention Education |
| Awareness of Smartphone Overdependence Treatment | |
| Intent to Seek Smartphone Education | Intent to Participate in Prevention Program |
| Smartphone Use Cases | Phone Use Case—Email |
| Phone Use Case—Messenger | |
| Phone Use Case—Making New Friends | |
| Phone Use Case—Scheduling | |
| Phone Use Case—Health | |
| Phone Use Case—Zoom Meetings | |
| Phone Use Case—Online Shopping | |
| Phone Use Case—Selling Goods and Services | |
| Phone Use Case—Banking | |
| Phone Use Case—Investment | |
| Phone Use Case—Gaming | |
| Phone Use Case—Watching Videos | |
| Phone Use Case—Listening Music | |
| Phone Use Case—Listening Radio | |
| Phone Use Case—Webtoon | |
| Phone Use Case—Photography | |
| Phone Use Case—Travel | |
| Phone Use Case—Adult Content | |
| Phone Use Case—Gambling | |
| Phone Use Case—News | |
| Phone Use Case—Educational Web Search | |
| Phone Use Case—Hobby Web Search | |
| Phone Use Case—Navigation | |
| Phone Use Case—Online Learning | |
| Smartphone Online Video Usage | |
| Phone Use Case Video—Short-Form Platform YouTube | |
| Phone Use Case Video—Short-Form Platform TikTok | |
| Phone Use Case Video—Short-Form Platform Reels | |
| Phone Use Case Video—Short-Form Platform, Etc. | |
| Phone Use Case Video—Short-Form Platform Never | |
| Phone Use Case Video—Short-Form Video Usage Portion | |
| Phone Use Case Video—Mostly Food | |
| Phone Use Case Video—Mostly Sports | |
| Phone Use Case Video—Mostly Fashion/Beauty | |
| Phone Use Case Video—Mostly Gaming | |
| Phone Use Case Video—Mostly Dramas/Variety Show | |
| Phone Use Case Video—Mostly Animation/Comics | |
| Phone Use Case Video—Mostly TV/Entertainment | |
| Phone Use Case Video—Mostly Music/Dance | |
| Phone Use Case Video—Mostly Talk/Streaming | |
| Phone Use Case Video—Mostly Movies | |
| Phone Use Case Video—Mostly Products | |
| Phone Use Case Video—Mostly Current Affairs | |
| Phone Use Case Video—Mostly Lifestyle | |
| Phone Use Case Video—Mostly Edu | |
| Phone Use Case Video—Mostly Kids | |
| Phone Use Case Video—Mostly Vlog | |
| Phone Use Case Video—Mostly Other | |
| Home Environment | House |
| Apartment | |
| Mansion | |
| etc. | |
| Multicultural Family | |
| Single Parent Family | |
| Both Parents Work | |
| Monthly Family Income | |
| Parental Prevention Efforts | Complete Smartphone Use Restriction |
| Limit Smartphone Usage Time | |
| Restrict Smartphone Apps | |
| Teach Smartphone Usage | |
| Smartphone Use Pros and Cons | |
| Recommended Beneficial Smartphone Apps | |
| Use Beneficial Apps Together | |
| Use Beneficial Games Together | |
| Family Smartphone Rules | |
| Social Support | Family Support Generosity |
| Friend Support In Difficulty | |
| Society Fair Opportunities and Benefits |
| Domains/Constructs | Features |
|---|---|
| Self-Regulation Assessments | Smartphone Usage Avoidance While Walking |
| Smartphone Usage Habit Check | |
| Smartphone Usage History Check | |
| Digital Detox | |
| Designated Smartphone Placement | |
| Use Work Mode | |
| Direct Conversation | |
| Hobby Engagement | |
| Perceived Digital Competence and Risk | Perceived Phone Issues—Smartphone Usage Dependence Comparison |
| Perceived Phone Issues—Neg Side Effects on SNS | |
| Perceived Phone Issues—Neg Side Effects on Email | |
| Perceived Phone Issues—Neg Side Effects on Messenger | |
| Perceived Phone Issues—Neg Side Effects on New Friends | |
| Perceived Phone Issues—Neg Side Effects on Scheduling | |
| Perceived Phone Issues—Neg Side Effects on Health | |
| Perceived Phone Issues—Neg Side Effects on Zoom | |
| Perceived Phone Issues—Neg Side Effects on Shopping | |
| Perceived Phone Issues—Neg Side Effects on Selling | |
| Perceived Phone Issues—Neg Side Effects on Banking | |
| Perceived Phone Issues—Neg Side Effects on Investment | |
| Perceived Phone Issues—Neg Side Effects on Gaming | |
| Perceived Phone Issues—Neg Side Effects on Watching Videos | |
| Perceived Phone Issues—Neg Side Effects on Listening Music | |
| Perceived Phone Issues—Neg Side Effects on Listening Radio | |
| Perceived Phone Issues—Neg Side Effects on Webtoon | |
| Perceived Phone Issues—Neg Side Effects on Photography | |
| Perceived Phone Issues—Neg Side Effects on Travel | |
| Perceived Phone Issues—Neg Side Effects on X-Rated Content | |
| Perceived Phone Issues—Neg Side Effects on Gambling Game | |
| Perceived Phone Issues—Neg Side Effects on News | |
| Perceived Phone Issues—Neg Side Effects on Edu | |
| Perceived Phone Issues—Neg Side Effects on Interests | |
| Perceived Phone Issues—Neg Side Effects on Navigation | |
| Perceived Phone Issues—Neg Side Effects on Distance Class | |
| Perceived Phone Issues—Excessive Smartphone Usage | |
| Perceived Phone Issues—Short-Form Video Usage Control Difficulty | |
| Perceived Competence—Necessary Information Access | |
| Perceived Competence—Assess Online Information Reliability | |
| Perceived Competence—Online Social Issue Engagement | |
| Perceived Competence—Digital Content Creation | |
| Perceived Competence—Online Privacy Awareness | |
| Perceived Competence—Use Online Information Academia Work | |
| Life Satisfaction | Relationship Satisfaction |
| Work Satisfaction | |
| Leisure Activities Satisfaction | |
| Overall Life Satisfaction | |
| Smartphone Consequences and Dependence | Smartphone Periodic Check Nervousness |
| Smartphone Low-Battery Nervousness | |
| Smartphone Usage Depression | |
| Smartphone Usage Physical Effects | |
| Smartphone Usage Sleep Issues | |
| Smartphone Communication Social Isolation | |
| Stress Relief Through Smartphone |
Appendix B. Hyperparameters for Our 4 Exemplar Models
| Model Name | Algorithm | Hyperparameters |
|---|---|---|
| Nest M4 model | Random Forest | n_estimators = 1967; max_depth = 81; min_samples_split = 4; min_samples_leaf = 1 |
| SmartCD Only | LightGBM | n_estimators = 254; learning_rate = 0.064495018055983; max_depth = 3; num_leaves = 222; min_child_samples = 17; feature_fraction = 0.469378476101846; bagging_fraction = 0.52804982292064; bagging_freq = 6; lambda_l1 = 0.186535833027839; lambda_l2 = 0.0000131738014410991 |
| Perceived DCR Only | XGBoost | num_boost_round = 674; subsample = 0.85597440455654; min_child_weight = 1; max_depth = 38; learning_rate = 0.0127554708475019; = 0.229654735805916; colsample_bytree = 0.287803548558039; reg_alpha = 0.00651358918568053; reg_lambda = 0.791652034688638 |
| Use Case Only | XGBoost | num_boost_round = 562; subsample = 0.583206150016204; min_child_weight = 1; max_depth = 74; learning_rate = 0.0113916452910645; = 0.00109214155684023; colsample_bytree = 0.300084001241431; reg_alpha = 0.277286668793397; reg_lambda = 0.0305140602390746 |
Appendix C. Sample Descriptives
Appendix C.1. Place-Stratified Descriptive Comparisons
| Variable Category | Variable | Metropolitan City (n = 831) | Medium/Small City (n = 714) | Town/Rural District (n = 328) | p-Value |
|---|---|---|---|---|---|
| Demographics | |||||
| Age (mean, SD) | 14.35 (2.35) | 14.35 (2.45) | 14.29 (2.4) | 0.917 | |
| Sex (Male; n (%)) | 401 (48.3%) | 355 (49.7%) | 144 (43.9%) | 0.215 | |
| Elementary School Students (n (%)) | 205 (24.7%) | 189 (26.5%) | 88 (26.8%) | 0.637 | |
| Middle School Students (n (%)) | 317 (38.1%) | 263 (36.8%) | 127 (38.7%) | 0.802 | |
| High School Students (n (%)) | 309 (37.2%) | 262 (36.7%) | 113 (34.5%) | 0.679 | |
| Home Environment | |||||
| House (n (%)) | 167 (20.1%) | 152 (21.3%) | 90 (27.4%) | 0.022 * | |
| Apartment (n (%)) | 473 (56.9%) | 394 (55.2%) | 172 (52.4%) | 0.377 | |
| Mansion (n (%)) | 170 (20.5%) | 129 (18.1%) | 53 (16.2%) | 0.197 | |
| Other Housing (n (%)) | 21 (2.5%) | 39 (5.5%) | 13 (4.0%) | - | |
| Multicultural Family (n (%)) | 7 (0.8%) | 2 (0.3%) | 4 (1.2%) | - | |
| Single-Parent Family (n (%)) | 55 (6.6%) | 60 (8.4%) | 31 (9.5%) | 0.200 | |
| Both Parents Working (n (%)) | 588 (70.8%) | 520 (72.8%) | 236 (72.0%) | 0.664 | |
| Monthly Household Income (mean, SD) | 3.26 (0.75) | 3.2 (0.82) | 3.23 (0.77) | 0.424 | |
| Smartphone Use Cases | |||||
| Email (M (SD)) | 1.85 (1.89) | 1.89 (1.89) | 1.98 (2.05) | 0.601 | |
| Messenger (M (SD)) | 5.31 (1.46) | 5.41 (1.42) | 5.02 (1.75) | <0.001 *** | |
| Making New Friends (M (SD)) | 1.45 (1.98) | 1.25 (1.79) | 1.33 (1.85) | 0.126 | |
| Scheduling (M (SD)) | 2.06 (2.13) | 1.86 (2.06) | 1.62 (2.08) | 0.004 ** | |
| Health (M (SD)) | 1.76 (2.04) | 1.59 (1.91) | 1.46 (1.98) | 0.045 * | |
| Zoom Meetings (M (SD)) | 0.73 (1.57) | 0.54 (1.33) | 0.59 (1.41) | 0.030 * | |
| Online Shopping (M (SD)) | 2.1 (2.16) | 2.04 (2.13) | 2.18 (2.32) | 0.596 | |
| Selling Goods and Services (M (SD)) | 1.65 (2.06) | 1.51 (2.0) | 1.77 (2.27) | 0.149 | |
| Banking (M (SD)) | 1.49 (1.93) | 1.39 (1.85) | 1.35 (2.01) | 0.411 | |
| Investment (M (SD)) | 0.86 (1.52) | 0.63 (1.28) | 0.62 (1.29) | <0.001 *** | |
| Gaming (M (SD)) | 4.89 (1.83) | 4.92 (1.73) | 4.63 (1.97) | 0.052 | |
| Watching Videos (M (SD)) | 5.25 (1.62) | 5.32 (1.58) | 5.02 (1.81) | 0.018 * | |
| Listening Music (M (SD)) | 4.51 (1.97) | 4.48 (2.04) | 4.03 (2.35) | <0.001 *** | |
| Listening Radio (M (SD)) | 1.55 (2.03) | 1.69 (2.08) | 1.54 (2.09) | 0.380 | |
| Webtoon (M (SD)) | 3.35 (2.27) | 3.32 (2.2) | 3.11 (2.33) | 0.241 | |
| Variable Category | Variable | Metropolitan City (n = 831) | Medium/Small City (n = 714) | Town/Rural District (n = 328) | p-Value |
|---|---|---|---|---|---|
| Photography (M (SD)) | 3.5 (1.96) | 3.43 (1.94) | 3.42 (2.2) | 0.745 | |
| Travel (M (SD)) | 1.71 (1.94) | 1.6 (1.86) | 1.84 (2.04) | 0.144 | |
| Adult Content (M (SD)) | 0.5 (1.15) | 0.33 (0.94) | 0.3 (0.94) | <0.001 *** | |
| Gambling (M (SD)) | 0.48 (1.2) | 0.29 (0.87) | 0.32 (1.04) | <0.001 *** | |
| News (M (SD)) | 2.57 (2.21) | 2.3 (2.04) | 2.16 (2.16) | 0.004 ** | |
| Educational Web Search (M (SD)) | 4.06 (1.81) | 3.84 (1.78) | 3.64 (2.26) | 0.002 ** | |
| Hobby Web Search (M (SD)) | 3.87 (1.9) | 3.73 (1.9) | 3.68 (2.25) | 0.234 | |
| Navigation (M (SD)) | 2.42 (1.92) | 2.37 (1.95) | 2.12 (2.0) | 0.049 * | |
| Online Learning (M (SD)) | 3.63 (2.23) | 3.45 (2.2) | 3.62 (2.33) | 0.274 | |
| Smartphone Online Video Usage (n (%)) | 798 (96.0%) | 694 (97.2%) | 313 (95.4%) | 0.285 | |
| Short-Form Platform YouTube (n (%)) | 443 (53.3%) | 315 (44.1%) | 162 (49.4%) | 0.002 ** | |
| Short-Form Platform TikTok (n (%)) | 145 (17.4%) | 165 (23.1%) | 68 (20.7%) | 0.021 * | |
| Short-Form Platform Reels (n (%)) | 77 (9.3%) | 81 (11.3%) | 34 (10.4%) | 0.405 | |
| Short-Form Platform, Etc. (n (%)) | 8 (1.0%) | 6 (0.8%) | 2 (0.6%) | - | |
| Short-Form Platform Never (n (%)) | 125 (15.0%) | 127 (17.8%) | 47 (14.3%) | 0.229 | |
| Short-Form Video Usage (M (SD)) | 1.67 (1.1) | 1.73 (1.15) | 1.8 (1.17) | 0.207 | |
| Mostly Food (n (%)) | 130 (15.6%) | 80 (11.2%) | 47 (14.3%) | 0.038 * | |
| Mostly Sports (n (%)) | 40 (4.8%) | 39 (5.5%) | 14 (4.3%) | - | |
| Mostly Fashion/Beauty (n (%)) | 38 (4.6%) | 37 (5.2%) | 20 (6.1%) | - | |
| Mostly Gaming (n (%)) | 250 (30.1%) | 222 (31.1%) | 90 (27.4%) | 0.489 | |
| Mostly Dramas/Variety Show (n (%)) | 83 (10.0%) | 54 (7.6%) | 24 (7.3%) | - | |
| Mostly Animation/Comics (n (%)) | 56 (6.7%) | 63 (8.8%) | 24 (7.3%) | - | |
| Mostly TV/Entertainment (n (%)) | 42 (5.1%) | 46 (6.4%) | 19 (5.8%) | - | |
| Mostly Music/Dance (n (%)) | 45 (5.4%) | 53 (7.4%) | 24 (7.3%) | - | |
| Mostly Talk/Streaming (n (%)) | 17 (2.0%) | 16 (2.2%) | 5 (1.5%) | - | |
| Mostly Movies (n (%)) | 18 (2.2%) | 9 (1.3%) | 8 (2.4%) | - | |
| Mostly Products (n (%)) | 12 (1.4%) | 11 (1.5%) | 2 (0.6%) | - | |
| Mostly Current Affairs (n (%)) | 3 (0.4%) | 10 (1.4%) | 2 (0.6%) | - | |
| Mostly Lifestyle (n (%)) | 4 (0.5%) | 2 (0.3%) | 5 (1.5%) | - | |
| Mostly Edu (n (%)) | 49 (5.9%) | 34 (4.8%) | 26 (7.9%) | - | |
| Mostly Kids (n (%)) | 6 (0.7%) | 11 (1.5%) | 2 (0.6%) | - | |
| Mostly Vlog (n (%)) | 4 (0.5%) | 7 (1.0%) | 1 (0.3%) | - | |
| Mostly Other (n (%)) | 1 (0.1%) | 0 (0.0%) | 0 (0.0%) | - |
| Variable Category | Variable | Metropolitan City (n = 831) | Medium/Small City (n = 714) | Town/Rural District (n = 328) | p-Value |
|---|---|---|---|---|---|
| Perceived Digital Risk | |||||
| Smartphone Usage Dependence Comparison (M (SD)) | 2.71 (0.74) | 2.76 (0.75) | 2.72 (0.78) | 0.376 | |
| Side Effects on SNS (n (%)) | 48 (5.8%) | 56 (7.8%) | 22 (6.7%) | - | |
| Side Effects on Email (n (%)) | 15 (1.8%) | 11 (1.5%) | 4 (1.2%) | - | |
| Side Effects on Messenger (n (%)) | 23 (2.8%) | 28 (3.9%) | 16 (4.9%) | - | |
| Side Effects on New Friends (n (%)) | 21 (2.5%) | 16 (2.2%) | 14 (4.3%) | - | |
| Side Effects on Scheduling (n (%)) | 13 (1.6%) | 4 (0.6%) | 0 (0.0%) | - | |
| Side Effects on Health (n (%)) | 7 (0.8%) | 2 (0.3%) | 1 (0.3%) | - | |
| Side Effects on Zoom (n (%)) | 3 (0.4%) | 5 (0.7%) | 0 (0.0%) | - | |
| Side Effects on Shopping (n (%)) | 34 (4.1%) | 24 (3.4%) | 13 (4.0%) | - | |
| Side Effects on Selling (n (%)) | 8 (1.0%) | 7 (1.0%) | 6 (1.8%) | - | |
| Side Effects on Banking (n (%)) | 1 (0.1%) | 3 (0.4%) | 2 (0.6%) | - | |
| Side Effects on Investment (n (%)) | 9 (1.1%) | 3 (0.4%) | 3 (0.9%) | - | |
| Side Effects on Gaming (n (%)) | 353 (42.5%) | 313 (43.8%) | 108 (32.9%) | 0.003 ** | |
| Side Effects on Watching Videos (n (%)) | 68 (8.2%) | 52 (7.3%) | 21 (6.4%) | - | |
| Side Effects on Listening Music (n (%)) | 0 (0.0%) | 2 (0.3%) | 3 (0.9%) | - | |
| Side Effects on Listening Radio (n (%)) | 1 (0.1%) | 1 (0.1%) | 1 (0.3%) | - | |
| Side Effects on Webtoon (n (%)) | 28 (3.4%) | 13 (1.8%) | 7 (2.1%) | - | |
| Side Effects on Photography (n (%)) | 2 (0.2%) | 0 (0.0%) | 1 (0.3%) | - | |
| Side Effects on Travel (n (%)) | 1 (0.1%) | 1 (0.1%) | 0 (0.0%) | - | |
| Side Effects on X-Rated Content (n (%)) | 30 (3.6%) | 9 (1.3%) | 8 (2.4%) | - | |
| Side Effects on Gambling Game (n (%)) | 2 (0.2%) | 12 (1.7%) | 2 (0.6%) | - | |
| Side Effects on News (n (%)) | 3 (0.4%) | 1 (0.1%) | 2 (0.6%) | - | |
| Side Effects on Edu (n (%)) | 1 (0.1%) | 3 (0.4%) | 0 (0.0%) | - | |
| Side Effects on Interests (n (%)) | 1 (0.1%) | 0 (0.0%) | 0 (0.0%) | - | |
| Side Effects on Navigation (n (%)) | 2 (0.2%) | 3 (0.4%) | 0 (0.0%) | - | |
| Side Effects on Distance Class (n (%)) | 1 (0.1%) | 5 (0.7%) | 4 (1.2%) | - | |
| Excessive Smartphone Usage (M (SD)) | 2.57 (0.69) | 2.62 (0.69) | 2.62 (0.77) | 0.218 | |
| Short-Form Video Usage Control Difficulty (M (SD)) | 1.71 (1.09) | 1.81 (1.15) | 1.81 (1.08) | 0.139 | |
| Perceived Digital Competence | |||||
| Necessary Information Access (M (SD)) | 3.25 (0.64) | 3.25 (0.66) | 3.3 (0.67) | 0.404 | |
| Assess Online Information Reliability (M (SD)) | 2.98 (0.75) | 2.94 (0.77) | 3.05 (0.78) | 0.070 | |
| Online Social Issue Engagement (M (SD)) | 2.8 (0.85) | 2.7 (0.85) | 2.81 (0.81) | 0.037 * | |
| Digital Content Creation (M (SD)) | 2.49 (0.98) | 2.43 (0.98) | 2.62 (0.99) | 0.012 * | |
| Online Privacy Awareness (M (SD)) | 2.66 (0.88) | 2.57 (0.86) | 2.79 (0.86) | <0.001 *** | |
| Use Online Information for Academia/Work (M (SD)) | 2.89 (0.87) | 2.67 (0.94) | 2.81 (0.92) | <0.001 *** | |
Appendix C.2. Training Versus Test Set Descriptive Comparisons
| Variable Category | Variable | Metropolitan City (n = 831) | Medium/Small City (n = 714) | Town/Rural District (n = 328) | p-Value |
|---|---|---|---|---|---|
| Smartphone Consequences and Dependence | |||||
| Low-Battery Nervousness (M (SD)) | 2.71 (0.83) | 2.85 (0.86) | 2.75 (0.85) | 0.004 ** | |
| Smartphone Usage Depression (M (SD)) | 2.16 (0.87) | 2.23 (0.81) | 2.17 (0.83) | 0.250 | |
| Physical Effects (M (SD)) | 2.27 (0.89) | 2.35 (0.86) | 2.32 (0.89) | 0.170 | |
| Periodic Check Nervousness (M (SD)) | 2.57 (0.75) | 2.61 (0.76) | 2.52 (0.73) | 0.175 | |
| Smartphone Usage Sleep Issues (M (SD)) | 2.21 (0.84) | 2.29 (0.86) | 2.21 (0.89) | 0.174 | |
| Social Isolation (M (SD)) | 2.05 (0.79) | 2.13 (0.81) | 2.11 (0.73) | 0.133 | |
| Stress Relief Through Smartphone (M (SD)) | 2.41 (0.83) | 2.43 (0.85) | 2.35 (0.85) | 0.437 | |
| Preventative Education | |||||
| Received Preventive Education (n (%)) | 589 (31.4%) | 466 (31.1%) | 123 (32.8%) | 0.819 | |
| Awareness of Treatment Options (n (%)) | 958 (51.1%) | 768 (51.3%) | 190 (50.7%) | 0.979 | |
| Intent to Seek Smartphone Education | |||||
| Participation Intention (M (SD)) | 2.25 (0.71) | 2.21 (0.72) | 2.27 (0.74) | 0.370 | |
| Parental Prevention Efforts | |||||
| Complete Restriction (n (%)) | 81 (9.7%) | 71 (9.9%) | 33 (10.1%) | 0.984 | |
| Teaches How to Use the Phone (n (%)) | 397 (47.8%) | 284 (39.8%) | 130 (39.6%) | 0.002 ** | |
| Restrict Smartphone Apps (n (%)) | 508 (61.1%) | 439 (61.5%) | 185 (56.4%) | 0.256 | |
| Teaches Pros and Cons (n (%)) | 514 (61.9%) | 422 (59.1%) | 176 (53.7%) | 0.037 * | |
| Recommends Good Apps (n (%)) | 396 (47.7%) | 277 (38.8%) | 152 (46.3%) | <0.001 *** | |
| Uses Good Apps Together (n (%)) | 252 (30.3%) | 210 (29.4%) | 93 (28.4%) | 0.793 | |
| Plays Good Games Together (n (%)) | 225 (27.1%) | 206 (28.9%) | 75 (22.9%) | 0.130 | |
| Family Smartphone Rules (n (%)) | 354 (42.6%) | 272 (38.1%) | 133 (40.5%) | 0.199 | |
| Social Support | |||||
| Family Support (M (SD)) | 3.29 (0.69) | 3.17 (0.75) | 3.26 (0.66) | 0.005 ** | |
| Friend Support (M (SD)) | 3.13 (0.67) | 3.07 (0.69) | 3.17 (0.68) | 0.044 * | |
| Societal Fairness Perception (M (SD)) | 2.93 (0.71) | 2.81 (0.75) | 3.03 (0.79) | <0.001 *** | |
| Variable Category | Variable | Metropolitan City (n = 831) | Medium/Small City (n = 714) | Town/Rural District (n = 328) | p-Value |
|---|---|---|---|---|---|
| Social Support | |||||
| Family Support (M (SD)) | 3.29 (0.69) | 3.17 (0.75) | 3.26 (0.66) | 0.005 ** | |
| Friend Support (M (SD)) | 3.13 (0.67) | 3.07 (0.69) | 3.17 (0.68) | 0.044 * | |
| Societal Fairness Perception (M (SD)) | 2.93 (0.71) | 2.81 (0.75) | 3.03 (0.79) | <0.001 *** | |
| Self-Regulation Assessments | |||||
| Smartphone Usage Avoidance While Walking (n (%)) | 518 (62.3%) | 455 (63.7%) | 223 (68.0%) | 0.195 | |
| Smartphone Usage Habit Check (n (%)) | 226 (27.2%) | 186 (26.1%) | 96 (29.3%) | 0.554 | |
| Smartphone Use History Check (n (%)) | 164 (19.7%) | 162 (22.7%) | 72 (22.0%) | 0.347 | |
| Digital Detox (n (%)) | 210 (25.3%) | 153 (21.4%) | 55 (16.8%) | 0.006 ** | |
| Designated Placement (n (%)) | 286 (34.4%) | 200 (28.0%) | 105 (32.0%) | 0.026 * | |
| Use of Work Mode (n (%)) | 414 (49.8%) | 316 (44.3%) | 136 (41.5%) | 0.015 * | |
| Engaging in Conversation (n (%)) | 374 (45.0%) | 285 (39.9%) | 134 (40.9%) | 0.109 | |
| Hobby Engagement (n (%)) | 208 (25.0%) | 212 (29.7%) | 94 (28.7%) | 0.106 | |
| Life Satisfaction | |||||
| Relationship Satisfaction (M (SD)) | 3.25 (0.58) | 3.28 (0.6) | 3.31 (0.6) | 0.193 | |
| Work Satisfaction (M (SD)) | 2.91 (0.7) | 2.89 (0.73) | 2.99 (0.72) | 0.077 | |
| Leisure Satisfaction (M (SD)) | 2.86 (0.7) | 2.84 (0.71) | 2.91 (0.77) | 0.300 | |
| Overall Life Satisfaction (M (SD)) | 3.08 (0.57) | 3.04 (0.59) | 3.08 (0.65) | 0.462 | |
| Variable Category | Variable | Total Sample (N = 1873) | Training Set (n = 1498) | Test Set (n = 375) | p-Value |
|---|---|---|---|---|---|
| Demographics | |||||
| Age (mean, SD) | 14.34 (2.40) | 14.34 (2.39) | 14.34 (2.42) | 1.000 | |
| Sex (Male; n (%)) | 900 (48.1%) | 728 (48.6%) | 172 (45.9%) | 0.639 | |
| Elementary School Students (n (%)) | 482 (25.7%) | 389 (26.0%) | 93 (24.8%) | 0.898 | |
| Middle School Students (n (%)) | 707 (37.7%) | 565 (37.7%) | 142 (37.9%) | 0.999 | |
| High School Students (n (%)) | 684 (36.5%) | 544 (36.3%) | 140 (37.3%) | 0.935 | |
| Urbanicity | |||||
| Metropolitan City (n (%)) | 831 (44.4%) | 656 (43.8%) | 175 (46.7%) | 0.605 | |
| Medium or Small City (n (%)) | 714 (38.1%) | 571 (38.1%) | 143 (38.1%) | 1.000 | |
| Town or Rural District (n (%)) | 328 (17.5%) | 271 (18.1%) | 57 (15.2%) | 0.420 | |
| Home Environment | |||||
| House (n (%)) | 409 (21.8%) | 331 (22.1%) | 78 (20.8%) | 0.863 | |
| Apartment (n (%)) | 1039 (55.5%) | 829 (55.3%) | 210 (56.0%) | 0.974 | |
| Mansion (n (%)) | 352 (18.8%) | 276 (18.4%) | 76 (20.3%) | 0.716 | |
| Other Housing (n (%)) | 73 (3.9%) | 62 (4.1%) | 11 (2.9%) | - | |
| Multicultural Family (n (%)) | 13 (0.7%) | 11 (0.7%) | 2 (0.5%) | - | |
| Single-Parent Family (n (%)) | 146 (7.8%) | 114 (7.6%) | 32 (8.5%) | 0.837 | |
| Both Parents Working (n (%)) | 1344 (71.8%) | 1086 (72.5%) | 258 (68.8%) | 0.364 | |
| Monthly Household Income (mean, SD) | 3.23 (0.78) | 3.24 (0.79) | 3.18 (0.76) | 0.442 | |
| Variable Category | Variable | Total Sample (N = 1873) | Training Set (n = 1498) | Test Set (n = 375) | p-Value |
|---|---|---|---|---|---|
| Smartphone Use Cases | |||||
| Email (M (SD)) | 1.89 (1.91) | 1.89 (1.94) | 1.87 (1.81) | 0.983 | |
| Messenger (M (SD)) | 5.3 (1.51) | 5.29 (1.51) | 5.32 (1.49) | 0.966 | |
| Making New Friends (M (SD)) | 1.35 (1.89) | 1.36 (1.89) | 1.3 (1.9) | 0.857 | |
| Scheduling (M (SD)) | 1.91 (2.1) | 1.89 (2.11) | 2.0 (2.06) | 0.652 | |
| Health (M (SD)) | 1.64 (1.98) | 1.63 (1.97) | 1.67 (2.03) | 0.945 | |
| Zoom Meetings (M (SD)) | 0.63 (1.46) | 0.64 (1.47) | 0.61 (1.4) | 0.938 | |
| Online Shopping (M (SD)) | 2.09 (2.17) | 2.08 (2.17) | 2.13 (2.18) | 0.934 | |
| Selling Goods and Services (M (SD)) | 1.62 (2.08) | 1.62 (2.08) | 1.61 (2.07) | 0.987 | |
| Banking (M (SD)) | 1.43 (1.91) | 1.47 (1.94) | 1.24 (1.78) | 0.110 | |
| Investment (M (SD)) | 0.73 (1.4) | 0.71 (1.36) | 0.81 (1.54) | 0.529 | |
| Gaming (M (SD)) | 4.85 (1.82) | 4.84 (1.85) | 4.92 (1.67) | 0.718 | |
| Watching Videos (M (SD)) | 5.24 (1.64) | 5.22 (1.65) | 5.3 (1.6) | 0.695 | |
| Listening Music (M (SD)) | 4.42 (2.07) | 4.44 (2.05) | 4.32 (2.16) | 0.625 | |
| Listening Radio (M (SD)) | 1.6 (2.06) | 1.61 (2.07) | 1.58 (2.02) | 0.976 | |
| Webtoon (M (SD)) | 3.3 (2.25) | 3.27 (2.25) | 3.42 (2.28) | 0.519 | |
| Photography (M (SD)) | 3.46 (2.0) | 3.46 (2.02) | 3.49 (1.91) | 0.967 | |
| Travel (M (SD)) | 1.69 (1.93) | 1.71 (1.94) | 1.61 (1.86) | 0.652 | |
| Adult Content (M (SD)) | 0.4 (1.04) | 0.4 (1.04) | 0.41 (1.06) | 0.956 | |
| Gambling (M (SD)) | 0.38 (1.06) | 0.37 (1.04) | 0.43 (1.13) | 0.570 | |
| News (M (SD)) | 2.4 (2.14) | 2.38 (2.16) | 2.47 (2.05) | 0.770 | |
| Educational Web Search (M (SD)) | 3.9 (1.89) | 3.91 (1.91) | 3.88 (1.82) | 0.971 | |
| Hobby Web Search (M (SD)) | 3.78 (1.97) | 3.78 (1.96) | 3.81 (2.0) | 0.947 | |
| Navigation (M (SD)) | 2.35 (1.95) | 2.34 (1.97) | 2.37 (1.88) | 0.978 | |
| Online Learning (M (SD)) | 3.56 (2.23) | 3.56 (2.26) | 3.55 (2.13) | 0.999 | |
| Smartphone Online Video Usage (n (%)) | 1805 (96.4%) | 1441 (96.2%) | 364 (97.1%) | 0.722 | |
| Short-Form Platform YouTube (n (%)) | 920 (49.1%) | 740 (49.4%) | 180 (48.0%) | 0.889 | |
| Short-Form Platform TikTok (n (%)) | 378 (20.2%) | 294 (19.6%) | 84 (22.4%) | 0.489 | |
| Short-Form Platform Reels (n (%)) | 192 (10.3%) | 146 (9.7%) | 46 (12.3%) | 0.355 | |
| Short-Form Platform, Etc. (n (%)) | 16 (0.9%) | 13 (0.9%) | 3 (0.8%) | 0.992 | |
| Short-Form Platform Never (n (%)) | 299 (16.0%) | 248 (16.6%) | 51 (13.6%) | 0.377 | |
| Short-Form Video Usage (M (SD)) | 1.72 (1.13) | 1.69 (1.13) | 1.83 (1.13) | 0.109 | |
| Variable Category | Variable | Total Sample (N = 1873) | Training Set (n = 1498) | Test Set (n = 375) | p-Value |
|---|---|---|---|---|---|
| Smartphone Use Cases | |||||
| Mostly Food (n (%)) | 929 (49.6%) | 742 (49.5%) | 187 (49.9%) | 0.897 | |
| Mostly Sports (n (%)) | 586 (31.3%) | 469 (31.3%) | 117 (31.2%) | 0.961 | |
| Mostly Fashion/Beauty (n (%)) | 429 (22.9%) | 337 (22.5%) | 92 (24.5%) | 0.388 | |
| Mostly Gaming (n (%)) | 770 (41.1%) | 616 (41.1%) | 154 (41.1%) | 0.918 | |
| Mostly Dramas/Variety Show (n (%)) | 730 (39.0%) | 580 (38.7%) | 150 (40.0%) | 0.642 | |
| Mostly Animation/Comics (n (%)) | 631 (33.7%) | 510 (34.0%) | 121 (32.3%) | 0.541 | |
| Mostly TV/Entertainment (n (%)) | 620 (33.1%) | 491 (32.8%) | 129 (34.4%) | 0.548 | |
| Mostly Music/Dance (n (%)) | 612 (32.7%) | 491 (32.8%) | 121 (32.3%) | 0.869 | |
| Mostly Talk/Streaming (n (%)) | 563 (30.1%) | 446 (29.8%) | 117 (31.2%) | 0.607 | |
| Mostly Movies (n (%)) | 537 (28.7%) | 424 (28.3%) | 113 (30.1%) | 0.500 | |
| Mostly Products (n (%)) | 529 (28.2%) | 419 (28.0%) | 110 (29.3%) | 0.625 | |
| Mostly Current Affairs (n (%)) | 497 (26.5%) | 394 (26.3%) | 103 (27.5%) | 0.647 | |
| Mostly Lifestyle (n (%)) | 493 (26.3%) | 394 (26.3%) | 99 (26.4%) | 0.974 | |
| Mostly Edu (n (%)) | 488 (26.1%) | 391 (26.1%) | 97 (25.9%) | 0.946 | |
| Mostly Kids (n (%)) | 439 (23.4%) | 350 (23.4%) | 89 (23.7%) | 0.879 | |
| Mostly Vlog (n (%)) | 1032 (55.2%) | 775 (54.6%) | 257 (57.1%) | 0.703 | |
| Mostly Other (n (%)) | 1870 (99.8%) | 1496 (99.9%) | 374 (99.7%) | 0.323 | |
| Perceived Digital Risk | |||||
| Smartphone Usage Dependence Comparison (M (SD)) | 2.73 (0.75) | 2.72 (0.74) | 2.74 (0.79) | 0.889 | |
| Side Effects on SNS (n (%)) | 126 (6.7%) | 112 (7.5%) | 14 (3.7%) | - | |
| Side Effects on Email (n (%)) | 30 (1.6%) | 24 (1.6%) | 6 (1.6%) | - | |
| Side Effects on Messenger (n (%)) | 67 (3.6%) | 53 (3.5%) | 14 (3.7%) | - | |
| Side Effects on New Friends (n (%)) | 51 (2.7%) | 37 (2.5%) | 14 (3.7%) | - | |
| Side Effects on Scheduling (n (%)) | 17 (0.9%) | 12 (0.8%) | 5 (1.3%) | - | |
| Side Effects on Health (n (%)) | 10 (0.5%) | 10 (0.7%) | 0 (0.0%) | - | |
| Side Effects on Zoom (n (%)) | 8 (0.4%) | 7 (0.5%) | 1 (0.3%) | - | |
| Side Effects on Shopping (n (%)) | 71 (3.8%) | 55 (3.7%) | 16 (4.3%) | - | |
| Side Effects on Selling (n (%)) | 21 (1.1%) | 19 (1.3%) | 2 (0.5%) | - | |
| Side Effects on Banking (n (%)) | 6 (0.3%) | 5 (0.3%) | 1 (0.3%) | - | |
| Side Effects on Investment (n (%)) | 15 (0.8%) | 12 (0.8%) | 3 (0.8%) | - | |
| Side Effects on Gaming (n (%)) | 774 (41.3%) | 607 (40.5%) | 167 (44.5%) | 0.369 | |
| Variable Category | Variable | Total Sample (N = 1873) | Training Set (n = 1498) | Test Set (n = 375) | p-Value |
|---|---|---|---|---|---|
| Side Effects on Watching Videos (n (%)) | 141 (7.5%) | 113 (7.5%) | 28 (7.5%) | - | |
| Side Effects on Listening Music (n (%)) | 5 (0.3%) | 5 (0.3%) | 0 (0.0%) | - | |
| Side Effects on Listening Radio (n (%)) | 3 (0.2%) | 3 (0.2%) | 0 (0.0%) | - | |
| Side Effects on Webtoon (n (%)) | 48 (2.6%) | 36 (2.4%) | 12 (3.2%) | - | |
| Side Effects on Photography (n (%)) | 3 (0.2%) | 2 (0.1%) | 1 (0.3%) | - | |
| Side Effects on Travel (n (%)) | 2 (0.1%) | 2 (0.1%) | 0 (0.0%) | - | |
| Side Effects on X-Rated Content (n (%)) | 47 (2.5%) | 35 (2.3%) | 12 (3.2%) | - | |
| Side Effects on Gambling Game (n (%)) | 16 (0.9%) | 13 (0.9%) | 3 (0.8%) | - | |
| Side Effects on News (n (%)) | 6 (0.3%) | 6 (0.4%) | 0 (0.0%) | - | |
| Side Effects on Edu (n (%)) | 4 (0.2%) | 4 (0.3%) | 0 (0.0%) | - | |
| Side Effects on Interests (n (%)) | 1 (0.1%) | 1 (0.1%) | 0 (0.0%) | - | |
| Side Effects on Navigation (n (%)) | 5 (0.3%) | 5 (0.3%) | 0 (0.0%) | - | |
| Side Effects on Distance Class (n (%)) | 10 (0.5%) | 5 (0.3%) | 5 (1.3%) | - | |
| Excessive Smartphone Usage (M (SD)) | 2.6 (0.71) | 2.6 (0.69) | 2.59 (0.75) | 0.947 | |
| Short-Form Video Usage Control Difficulty (M (SD)) | 1.76 (1.11) | 1.74 (1.12) | 1.85 (1.09) | 0.209 | |
| Perceived Digital Competence | |||||
| Necessary Information Access (M (SD)) | 3.26 (0.65) | 3.25 (0.66) | 3.29 (0.65) | 0.619 | |
| Assess Online Information Reliability (M (SD)) | 2.98 (0.76) | 2.97 (0.76) | 3.0 (0.75) | 0.791 | |
| Online Social Issue Engagement (M (SD)) | 2.77 (0.84) | 2.76 (0.85) | 2.78 (0.82) | 0.972 | |
| Digital Content Creation (M (SD)) | 2.49 (0.99) | 2.47 (0.99) | 2.57 (0.97) | 0.197 | |
| Online Privacy Awareness (M (SD)) | 2.65 (0.88) | 2.64 (0.88) | 2.68 (0.86) | 0.756 | |
| Use Online Information for Academia/Work (M (SD)) | 2.79 (0.91) | 2.79 (0.93) | 2.8 (0.85) | 0.981 | |
| Smartphone Consequences and Dependence | |||||
| Low-Battery Nervousness (M (SD)) | 2.77 (0.85) | 2.76 (0.85) | 2.79 (0.84) | 0.790 | |
| Smartphone Usage Depression (M (SD)) | 2.19 (0.84) | 2.18 (0.83) | 2.22 (0.9) | 0.740 | |
| Physical Effects (M (SD)) | 2.31 (0.88) | 2.31 (0.87) | 2.33 (0.91) | 0.923 | |
| Periodic Check Nervousness (M (SD)) | 2.58 (0.75) | 2.57 (0.75) | 2.6 (0.76) | 0.836 | |
| Smartphone Usage Sleep Issues (M (SD)) | 2.24 (0.86) | 2.23 (0.85) | 2.29 (0.9) | 0.539 | |
| Social Isolation (M (SD)) | 2.09 (0.79) | 2.08 (0.78) | 2.14 (0.8) | 0.494 | |
| Stress Relief Through Smartphone (M (SD)) | 2.41 (0.84) | 2.4 (0.84) | 2.42 (0.85) | 0.918 | |
| Variable Category | Variable | Total Sample (N = 1873) | Training Set (n = 1498) | Test Set (n = 375) | p-Value |
|---|---|---|---|---|---|
| Preventative Education | |||||
| Received Preventive Education (n (%)) | 589 (31.4%) | 466 (31.1%) | 123 (32.8%) | 0.819 | |
| Awareness of Treatment Options (n (%)) | 958 (51.1%) | 768 (51.3%) | 190 (50.7%) | 0.979 | |
| Intent to Seek Smartphone Education | |||||
| Participation Intention (M (SD)) | 2.24 (0.72) | 2.25 (0.73) | 2.2 (0.69) | 0.501 | |
| Parental Prevention Efforts | |||||
| Complete Restriction (n (%)) | 1132 (60.4%) | 912 (60.9%) | 220 (58.7%) | 0.735 | |
| Teaches How to Use the Phone (n (%)) | 811 (43.3%) | 652 (43.5%) | 159 (42.4%) | 0.926 | |
| Restrict Smartphone Apps (n (%)) | 1132 (60.4%) | 912 (60.9%) | 220 (58.7%) | 0.735 | |
| Teaches Pros and Cons (n (%)) | 1112 (59.4%) | 885 (59.1%) | 227 (60.5%) | 0.877 | |
| Recommends Good Apps (n (%)) | 825 (44.0%) | 650 (43.4%) | 175 (46.7%) | 0.521 | |
| Uses Good Apps Together (n (%)) | 555 (29.6%) | 439 (29.3%) | 116 (30.9%) | 0.827 | |
| Plays Good Games Together (n (%)) | 506 (27.0%) | 393 (26.2%) | 113 (30.1%) | 0.315 | |
| Family Smartphone Rules (n (%)) | 759 (40.5%) | 599 (40.0%) | 160 (42.7%) | 0.640 | |
| Social Support | |||||
| Family Support (M (SD)) | 3.24 (0.71) | 3.23 (0.71) | 3.27 (0.70) | 0.616 | |
| Friend Support (M (SD)) | 3.12 (0.68) | 3.11 (0.67) | 3.13 (0.70) | 0.940 | |
| Societal Fairness Perception (M (SD)) | 2.9 (0.75) | 2.91 (0.74) | 2.86 (0.76) | 0.520 | |
| Self-Regulation Assessments | |||||
| Smartphone Usage Avoidance While Walking (n (%)) | 1196 (63.9%) | 949 (63.4%) | 247 (65.9%) | 0.663 | |
| Smartphone Usage Habit Check (n (%)) | 508 (27.1%) | 408 (27.2%) | 100 (26.7%) | 0.976 | |
| Smartphone Use History Check (n (%)) | 398 (21.2%) | 311 (20.8%) | 87 (23.2%) | 0.587 | |
| Digital Detox (n (%)) | 418 (22.3%) | 349 (23.3%) | 69 (18.4%) | 0.126 | |
| Designated Placement (n (%)) | 591 (31.6%) | 468 (31.2%) | 123 (32.8%) | 0.845 | |
| Use of Work Mode (n (%)) | 866 (46.2%) | 689 (46.0%) | 177 (47.2%) | 0.916 | |
| Engaging in Conversation (n (%)) | 793 (42.3%) | 647 (43.2%) | 146 (38.9%) | 0.328 | |
| Hobby Engagement (n (%)) | 514 (27.4%) | 409 (27.3%) | 105 (28.0%) | 0.964 | |
| Life Satisfaction | |||||
| Relationship Satisfaction (M (SD)) | 3.27 (0.59) | 3.27 (0.60) | 3.25 (0.57) | 0.798 | |
| Work Satisfaction (M (SD)) | 2.92 (0.71) | 2.92 (0.70) | 2.9 (0.75) | 0.853 | |
| Leisure Satisfaction (M (SD)) | 2.86 (0.72) | 2.87 (0.72) | 2.82 (0.69) | 0.384 | |
| Overall Life Satisfaction (M (SD)) | 3.07 (0.59) | 3.06 (0.59) | 3.07 (0.62) | 0.969 | |
Appendix D. AI/ML Results
Appendix D.1. Performance Comparison for Nested AI/ML Classifiers
| Model | Name | Algorithm | AUC | Mean Val Loss | Test Loss | # Features |
|---|---|---|---|---|---|---|
| M0 | Demographics | RF | 0.51 | 0.69 | 0.69 | 5 |
| M1 | +Urbanicity | DT | 0.57 | 0.70 | 0.69 | 8 |
| M2 | +Intent to Seek Smartphone Edu | RF | 0.63 | 0.67 | 0.67 | 9 |
| M3 | +Preventative Education Experiences | LightGBM | 0.63 | 0.67 | 0.67 | 11 |
| M4 | +Smartphone Use Cases | RF | 0.81 | 0.58 | 0.55 | 59 |
| M5 | +Home Environment | LightGBM | 0.80 | 0.59 | 0.54 | 66 |
| M6 | +Parental Prevention Efforts | XGB | 0.82 | 0.58 | 0.53 | 75 |
| M7 | +Social Support | RF | 0.80 | 0.59 | 0.57 | 78 |
| M8 | +Self-Regulation Assessments | XGB | 0.82 | 0.56 | 0.54 | 86 |
| M9 | +Perceived Digital Competence and Risk | XGB | 0.89 | 0.48 | 0.47 | 120 |
| M10 | +Life Satisfaction | RF | 0.88 | 0.51 | 0.47 | 124 |
| M11 | +Smartphone Consequences and Dependence | XGB | 0.92 | 0.45 | 0.39 | 131 |
Appendix D.2. Performance Comparison Between Construct-Based AI/ML Classifiers
| Construct | Shorthand | Algorithm | AUC | Mean Val Loss | Test Loss | # Features |
|---|---|---|---|---|---|---|
| Smartphone Consequences and Dependence | Smart CD | LightGBM | 0.89 | 0.50 | 0.42 | 7 |
| Perceived Digital Competence and Risk | Perceived DCR | XGB | 0.84 | 0.52 | 0.49 | 34 |
| Smartphone Use Cases | Use Case | XGB | 0.80 | 0.59 | 0.54 | 48 |
| Self-Regulation Assessments | Self-Reg | RF | 0.64 | 0.67 | 0.66 | 8 |
| Parental Prevention Efforts | Par Prev | XGB | 0.62 | 0.68 | 0.67 | 9 |
| Intent to Seek Smartphone Edu | Intent Edu | LogReg | 0.61 | 0.67 | 0.67 | 1 |
| Urbanicity | Urb | LogReg | 0.58 | 0.69 | 0.69 | 3 |
| Home Environment | Home Envir | LogReg | 0.56 | 0.70 | 0.69 | 8 |
| Preventative Education Experiences | Prev Edu | DT | 0.55 | 0.69 | 0.69 | 2 |
| Life Satisfaction | Life Sat | RF | 0.54 | 0.69 | 0.69 | 4 |
| Social Support | SoSu | RF | 0.53 | 0.70 | 0.69 | 3 |
| Demographics | Demo | RF | 0.51 | 0.69 | 0.69 | 5 |
Appendix E. M4 (+Smartphone Use Cases) PDPs






Appendix F. Smart CD PDPs



Appendix G. Perceived DCR PDPs






Appendix H. Use Case Only PDPs







References
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| Construct | Variable | Metropolitan City | Medium or | Town or |
|---|---|---|---|---|
| Small City | Rural District | |||
| (n = 831) | (n = 714) | (n = 328) | ||
| Home Environment | House (n (%)) * | 167 (20.1%) | 152 (21.3%) | 90 (27.4%) |
| Smartphone Use Cases | Messenger (M (SD)) *** | 5.31 (1.46) | 5.41 (1.42) | 5.02 (1.75) |
| Scheduling (M (SD)) ** | 2.06 (2.13) | 1.86 (2.06) | 1.62 (2.08) | |
| Health (M (SD)) * | 1.76 (2.04) | 1.59 (1.91) | 1.46 (1.98) | |
| Zoom Meetings (M (SD)) * | 0.73 (1.57) | 0.54 (1.33) | 0.59 (1.41) | |
| Investment (M (SD)) *** | 0.86 (1.52) | 0.63 (1.28) | 0.62 (1.29) | |
| Watching Videos (M (SD)) * | 5.25 (1.62) | 5.32 (1.58) | 5.02 (1.81) | |
| Listening Music (M (SD)) *** | 4.51 (1.97) | 4.48 (2.04) | 4.03 (2.35) | |
| Adult Content (M (SD)) *** | 0.50 (1.15) | 0.33 (0.94) | 0.30 (0.94) | |
| Gambling (M (SD)) *** | 0.48 (1.20) | 0.29 (0.87) | 0.32 (1.04) | |
| News (M (SD)) ** | 2.57 (2.21) | 2.30 (2.04) | 2.16 (2.16) | |
| Educational Web Search (M (SD)) ** | 4.06 (1.81) | 3.84 (1.78) | 3.64 (2.26) | |
| Navigation (M (SD)) * | 2.42 (1.92) | 2.37 (1.95) | 2.12 (2.00) | |
| Short-Form YouTube (n (%)) ** | 443 (53.3%) | 315 (44.1%) | 162 (49.4%) | |
| TikTok (n (%)) * | 145 (17.4%) | 165 (23.1%) | 68 (20.7%) | |
| Mostly Food (n (%)) * | 130 (15.6%) | 80 (11.2%) | 47 (14.3%) | |
| Perceived Digital Competence and Risk | Gaming Side Effects (n (%)) ** | 353 (42.5%) | 313 (43.8%) | 108 (32.9%) |
| Issue Engagement (M (SD)) * | 2.80 (0.85) | 2.70 (0.85) | 2.81 (0.81) | |
| Content Creation (M (SD)) * | 2.49 (0.98) | 2.43 (0.98) | 2.62 (0.99) | |
| Privacy Awareness (M (SD)) *** | 2.66 (0.88) | 2.57 (0.86) | 2.79 (0.86) | |
| Info for School/Work (M (SD)) *** | 2.89 (0.87) | 2.67 (0.94) | 2.81 (0.92) | |
| Consequences and Dependence | Low-Battery Nervousness (M (SD)) ** | 2.71 (0.83) | 2.85 (0.86) | 2.75 (0.85) |
| Parental Prevention | Teaches Use (n (%)) ** | 397 (47.8%) | 284 (39.8%) | 130 (39.6%) |
| Teaches Pros/Cons (n (%)) * | 514 (61.9%) | 422 (59.1%) | 176 (53.7%) | |
| Recommends Apps (n (%)) *** | 396 (47.7%) | 277 (38.8%) | 152 (46.3%) | |
| Social Support | Family Support (M (SD)) ** | 3.29 (0.69) | 3.17 (0.75) | 3.26 (0.66) |
| Friend Support (M (SD)) * | 3.13 (0.67) | 3.07 (0.69) | 3.17 (0.68) | |
| Fairness Perception (M (SD)) *** | 2.93 (0.71) | 2.81 (0.75) | 3.03 (0.79) | |
| Self-Regulation | Digital Detox (n (%)) ** | 210 (25.3%) | 153 (21.4%) | 55 (16.8%) |
| Designated Placement (n (%)) * | 286 (34.4%) | 200 (28.0%) | 105 (32.0%) | |
| Work Mode (n (%)) * | 414 (49.8%) | 316 (44.3%) | 136 (41.5%) |
| Model Name/Construct | Shorthand | Algorithm | AUC | Mean Val Loss | Test Loss | Num Features |
|---|---|---|---|---|---|---|
| +Smartphone Use Cases | M4 | RF | 0.81 | 0.58 | 0.55 | 59 |
| Smartphone Consequences and Dependence | Smart CD | LightGBM | 0.89 | 0.50 | 0.42 | 7 |
| Perceived Digital Competence and Risk | Perceived DCR | XGB | 0.84 | 0.52 | 0.49 | 34 |
| Smartphone Use Cases | Use Case | XGB | 0.80 | 0.59 | 0.54 | 48 |
| Model | National AUC | Place-Stratified AUC | ||
|---|---|---|---|---|
| Metropolitan City | Medium or Small City | Town or Rural District | ||
| M4 (+Smartphone Use Cases) | 0.81 | 0.87 | 0.75 | 0.80 |
| Smart CD Construct | 0.89 | 0.91 | 0.87 | 0.87 |
| Perceived DCR Construct | 0.84 | 0.85 | 0.83 | 0.83 |
| Use Case Construct | 0.80 | 0.88 | 0.70 | 0.79 |
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Kim, A.H.; Lee, U.; Cho, Y.; Kim, S.; Shah, V. Adolescent Smartphone Overdependence in South Korea: A Place-Stratified Evaluation of Conceptually Informed AI/ML Modeling. Int. J. Environ. Res. Public Health 2025, 22, 1515. https://doi.org/10.3390/ijerph22101515
Kim AH, Lee U, Cho Y, Kim S, Shah V. Adolescent Smartphone Overdependence in South Korea: A Place-Stratified Evaluation of Conceptually Informed AI/ML Modeling. International Journal of Environmental Research and Public Health. 2025; 22(10):1515. https://doi.org/10.3390/ijerph22101515
Chicago/Turabian StyleKim, Andrew H., Uibin Lee, Yohan Cho, Sangmi Kim, and Vatsal Shah. 2025. "Adolescent Smartphone Overdependence in South Korea: A Place-Stratified Evaluation of Conceptually Informed AI/ML Modeling" International Journal of Environmental Research and Public Health 22, no. 10: 1515. https://doi.org/10.3390/ijerph22101515
APA StyleKim, A. H., Lee, U., Cho, Y., Kim, S., & Shah, V. (2025). Adolescent Smartphone Overdependence in South Korea: A Place-Stratified Evaluation of Conceptually Informed AI/ML Modeling. International Journal of Environmental Research and Public Health, 22(10), 1515. https://doi.org/10.3390/ijerph22101515

