3.1.1. Participant Characteristics

Participants were mostly female (*n* = 72, 85%) and caring for one child under the age of 5 years (*n* = 68, 80%). Of the 85 parent/caregiver–child dyad observations (*n* = 85), 47 were in high socio-economic status (SES) playground locations and 38 in low SES playground locations.

### 3.1.2. Mobile Device Use—Mode and Duration

During the observation period, caregiver MDU was observed among 70% (*n* = 59) of the caregiver–child dyads, 30% (*n* = 16) of parents/carers did not use their mobile device, with total caregiver MDU comprising 23.5% of the observed time. The most frequently observed mode of MDU was "Scrolling/typing" (*n* = 272, 75.5%), followed by telephone call (*n* = 50, 13.9%) and using the camera (*n* = 38, 10.5%). The duration of MDU was either short of "1–10 s" (*n* = 91) or almost a full minute ("51–60 s") (*n* = 92).

### 3.1.3. Caregiver Mobile Device Use and Caregiver Supervision

Table 1 presents a comparison of supervision behaviours between minutes of "No MDU" and minutes of "MDU". For all observed minutes, the proportion of "No supervision" was higher when using a mobile device (MDU) compared with "No MDU" (29.4% and 5.2%, respectively). The proportion of "Constant supervision" was similar for "MDU" (45.8%) and "No MDU" (43.6%). A significant association was found between MDU and caregiver supervision χ2(2) = 191.67, *p* ≤ 0.001.

**Table 1.** Caregiver supervision by minutes of no mobile device use (No MDU) compared with minutes of mobile device use (MDU).


3.1.4. Caregiver Mobile Device Use and Caregiver–Child Interaction

"Independent play" (32.6%, *n* = 500) and "Caregiver–child play" (35.4%, *n* = 542) each made up one-third of the interaction behaviour of all observed minutes (Table 2). However, the proportion of "Caregiver–child play" with MDU was half that of no MDU (20.3% and 40.0%, respectively), while the proportion of "Independent play" for MDU was double that of "No MDU" (50.3% compared with 27.2%, respectively). The results show similar proportions for "Verbal interaction" within the "MDU" and "No MDU" groups (22.2% and 20.8%, respectively). A significant association was found between MDU and caregiver–child interaction χ2(4) = 81.95, *p* ≤ 0.001.

**Table 2.** Caregiver–child interaction by minutes of no mobile device use (No MDU) compared with minutes of mobile device use (MDU).


 *p* ≤ 0.001.

### 3.1.5. Caregiver Mobile Device Use and Child Injury Potential

Increased child injury potential was observed among 9.5% (*n* = 146) of all observed minutes. The proportion of observed "Increased injury potential" for "No MDU" was 5.7% (*n* = 67) compared with 21.9% (*n* = 79) with "MDU" (Table 3). The highest proportion of "Increased injury potential" was observed in the "51–60 s" (*n* = 30, 32.6%) MDU duration category. When comparing child injury potential across the mode of caregiver MDU, the highest proportion of "Increased injury potential" was observed for "Telephone call" (*n* = 13, 26%).


**Table 3.** Child injury potential by minutes of no mobile device use (No MDU) compared with minutes of mobile device use (MDU).
