Nonviolent Communication Plus Personalised E-message for Parents

Recruitment rate is defined as the proportion of eligible or contacted candidates who actually agree to join the study (Number Enrolled / Number Eligible or Approached).

Retention rate is defined as the percentage of randomised participants retained and assessed with valid primary outcome data.

The Child-Parent Relationship Scale (CPRS-SF) is a 15-item scale for evaluating two dimensions of the relationship between parents and children: conflict and closeness. Items are rated on a 5-point Likert scale ranging from 1 ("strongly disagree") to 5 ("strongly agree"). Scores for closeness and conflict are calculated separately, with higher closeness scores indicating a stronger emotional bond and a supportive relationship between parents and children (Driscoll & Pianta, 2011). Higher conflict scores indicate greater conflict between parents and children. The internal consistency reliabilities were adequate in a Chinese sample (Cronbach's alpha = 0.78 to 0.81) (Tan et al., 2023).

The Parenting Sense of Competence Scale (PSOC) (Ngai et al., 2007) is a 17-item scale to measure parents' perceived competence in the parenting role. Each item is rated on a 6-point Likert scale ranging from 1 (strongly disagree) to 6 (strongly agree). Higher scores indicate greater competence in parenting. Cronbach's alpha was 0.93 in a Chinese sample.

The Family Communication Scale (FCS) is a 10-item scale used to measure family communication (Guo et al., 2021). Items are rated on a 5-point Likert scale, ranging from 1 ("strongly disagree") to 5 ("strongly agree"). A higher total score (range 10-50) indicates a higher level of positive family communication. The Chinese version of FCS showed good internal consistency (Cronbach's alpha = 0.91) and was stable over 1 month (intraclass correlation coefficient = 0.69).

The Generalized Anxiety Disorder (GAD)-7 scale is a 7-item instrument to assess anxiety symptoms in the past two weeks (Spitzer et al., 2006; Tong et al., 2016). Each item is scored from 0 to 3. The seven item scores are summed to yield a total score ranging from 0 to 21, with higher scores indicating greater anxiety symptom severity.

Evaluated through process evaluation metrics assessing perceived benefits, subjective changes in personal mental health, and happiness. Participants rate overall satisfaction on a 0-10 scale, with 0 indicating "very dissatisfied" and 10 indicating "very satisfied". Open-ended questions will also collect participants' comments and suggestions.