Table 2. Descriptive Statistics for EMA and Passive Predictors.
| Variables (range)a | Mean (SD) | ICC | Derived features |
|---|---|---|---|
| EMAs (4/d) | |||
| Happy (1-5) | 2.56 (1.00) | 0.57 | Happyb (avg), CM happy, CH happy, max happy |
| Miserable (1-5) | 1.78 (0.91) | 0.50 | Miserable (avg), CM miserable, CH miserable, max miserable |
| Angry (1-5) | 1.48 (0.74) | 0.53 | Angry (avg), CM angry,b CH angry, max angryb |
| Nervous (1-5) | 2.44 (1.09) | 0.61 | Nervous (avg), CM nervous, CH nervous, max nervous |
| Sad (1-5) | 2.05 (1.02) | 0.53 | Sad (avg), CM sad, CH sad, max sadb |
| Rumination (1-7) | 3.04 (1.78) | 0.59 | Ruminationb (avg), CM rumination,b CH rumination, max ruminationb |
| Worry (1-7) | 3.03 (1.74) | 0.59 | Worryb (avg), CM worry,b CH worry, max worryb |
| Agitation (1-7) | 2.12 (1.46) | 0.56 | Agitation (avg), CM agitation,b CH agitation, max agitationb |
| Hopelessness (1-4) | 2.04 (0.84) | 0.73 | Hopelessness (avg), CM hopelessness,b CH hopelessness, max hopelessness |
| Burden (1-7) | 2.30 (1.66) | 0.71 | Burdenb (avg), CM burden, CH burden, max burdenb |
| Close to others (1-7) | 3.69 (1.65) | 0.59 | Close to others (avg), CM close to others, CH close to others, max close to othersb |
| Self-efficacy (0-10) | 8.66 (1.95) | 0.72 | Self-efficacyb (avg), CM self-efficacyb, CH self-efficacyb, max self-efficacyb |
| Duration of death thoughts (0-4) | 0.36 (0.69) | 0.48 | Death thoughts durationb (avg), CM death thoughts duration, CH death thoughts duration, max death thoughts duration |
| Duration of SI (0-4) | 0.25 (0.56) | 0.49 | SI duration (avg), CM SI duration, CH SI duration, max SI duration |
| Intensity of SI (0-5) | 0.32 (0.71) | 0.48 | SI intensity (avg), CM SI intensity, CH SI intensity, max SI intensity |
| Evening EMA survey | |||
| Frequency of death thoughts (0-4) | 0.70 (1.04) | 0.50 | Death thoughts frequency, CM death thoughts frequency, CH death thoughts frequency |
| Frequency of SI (0-4) | 0.48 (0.89) | 0.46 | SI frequency,b CM SI frequency,b CH SI frequencyb |
| Intensity of SI (0-5) | 0.55 (1.04) | 0.37 | SI intensity, CM SI intensity, CH SI intensity |
| Negative relationship events, No. (%) | 554 (17.7) | 0.34 | Negative relationship events, CM negative relationship events, CH negative relationship events |
| Coping (0-6)c | 2.59 (1.84) | 0.48 | Coping,b CM Coping,b CH Copingb |
| Morning EMA survey | |||
| Sleep quality (0-4) | 2.13 (1.01) | 0.30 | Sleep quality, CM Sleep quality, CH sleep quality |
| NSSI presence, No. (%) | 100 (3.2) | 0.67 | NSSI, CM NSSI, CH NSSI |
| Alcohol in standard drinks, No. (%) | |||
| 0 | 1927 (84.4) | 0.24 | Alcohol, CM alcohol, CH alcohol |
| 1-2 | 201 (8.8) | ||
| 3-4 | 101 (4.4) | ||
| ≥5 | 54 (2.4) | ||
| Sensor wristband (daily) | |||
| Resting heart rate (beats per minute) | 70.23 (10.60) | 0.90 | Resting heart rate,b CM resting heart rate,b CH resting heart rateb |
| RMSSD in milliseconds | 35.07 (9.55) | 0.77 | RMSSD,b CM RMSSD,b CH RMSSDb |
| Activity in steps | 6309.55 (4725.48) | 0.44 | Total steps, CM total steps, CH total steps |
| Sleep duration, min | 487.18 (144.76) | 0.36 | Minutes asleep, CM minutes asleep,b CH minutes asleep |
Abbreviations: avg, average score across within-day EMAs; CH, change from cumulative mean; CM, time-varying cumulative mean; EMA, ecological momentary assessment; ICC, intraclass correlation; max, maximum score from within-day EMAs; NSSI, nonsuicidal self-injury; RMSSD, root mean square of successive difference from heart rate; SI, suicidal ideation.
a
For each variable range listed, higher numbers indicate higher value of the specified variable (ie, higher number for happy means more happiness).
b
Features were selected for further inclusion in the mixed-effects CART models.
c
Coping reflects the sum of 3 coping types: reframe, talk, and distract.