Supporting Parents & Kids Through Lockdown Experiences (SPARKLE).

Parent-rated conduct subscale of the SDQ; a five item subscale measuring oppositional, defiant and disruptive behaviour rated on a 3-point Likert scale (not true, somewhat true, and certainly true), with a mix of positive and negatively phrased items. Individual items' scores are summed to derive an overall symptoms subscale score. This measure is also collected at baseline (T1), prior to randomisation.

Parent-rated conduct subscale of the SDQ; a five item subscale measuring oppositional, defiant and disruptive behaviour rated on a 3-point Likert scale (not true, somewhat true, and certainly true), with a mix of positive and negatively phrased items. Individual items' scores are summed to derive an overall symptoms subscale score. This measure is also collected at baseline (T1), prior to randomisation.

Parent-rated emotional problems subscale of the SDQ; a five item subscale measuring fearfulness and anxiety rated on a 3-point Likert scale (not true, somewhat true, and certainly true) with positively phrased items. Individual items' scores are summed to derive an overall symptoms subscale score. This measure is also collected at baseline (T1), prior to randomisation.

This is based on five items routinely measured in Co-SPACE regarding children's behaviour, wellbeing, screen time use, education and future using a 4-point Likert scale (not at all, a little, quite a lot, a great deal). Individual questions' scores are summed to generate a single score. This measure is also collected at baseline (T1), prior to randomisation.

This is based on three items routinely collected in Co-SPACE relating to arguments between parents, parents and children and siblings which are measured on a 4-point Likert scale (not at all, a bit, a lot, completely). The three questions are summed to generate a total score. This measure is also collected at baseline (T1), prior to randomisation.

This is a widely validated 21-item self-report questionnaire measuring adult depression, anxiety and stress. Each of the subscales consists of seven items rated on a 4-point Likert scale (did not apply to me at all; applied to me to some degree, or some of the time; applied to me to a considerable degree, or a good part of the time, applied to me very much, or most of the time), which are summed to obtain a single subscale score. The subscales scores will be summed and multiplied by two to form a single psychological distress measure comparable to the DASS-42 measure. This measure is also collected at baseline (T1), prior to randomisation.

Parents will provide information about their child's age and gender, their own and their child's ethnicity, number of children in the family, number of rooms in the family home and access to outside space. This will be used for description of the sample. We will estimate family SES based on total household income, coded as < £16,000 | £16,000 - £29,999 | £30,000 - £59,999 | £60,000 - £89,999 | £90,000 - £119,999 | > £120,000 | Prefer not to say, likely collapsing small categories. Family characteristics and demographic measures are obtained for sample description and for moderation analyses

Parents will provide information on the pandemic-related restrictions they are currently facing. This will include details of the current lockdown policy in their local area, whether parents are working from home, and whether children are being home-schooled. COVID-19 pandemic lockdown circumstances are measured at baseline (T1) for moderation analyses and at one month (T2) and two months (T3) post-randomisation for descriptive purposes.

This five item subscale measures restlessness, overactivity and inattention rated on 3-point Likert scales (not true, somewhat true, and certainly true), with a mix of positive and negatively phrased items. Individual items' scores are summed to derive an overall symptoms subscale score. SDQ ADHD symptoms are measured at baseline (T1) for moderation analyses, and at one (T2) and two months (T3) post-randomisation for calculation of QALYs for the cost-effectiveness analysis.

This five item subscale measures difficulties in peer relationships and bullying rated on 3-point Likert scales (not true, somewhat true, and certainly true), with a mix of positive and negatively phrased items. Individual items' scores are summed to derive an overall peer problems subscale score. SDQ Peer Problems are measured at baseline (T1), and at one month (T2) and two months (T3) post-randomisation for calculation of QALYs for the cost-effectiveness analysis.

This five item subscale measures difficulties in peer relationships and bullying rated on 3-point Likert scales (not true, somewhat true, and certainly true), with positively phrased items. Individual items' scores are summed to derive an overall prosocial subscale score with higher scores indicating more prosocial behaviour. SDQ Prosocial Behaviour are measured at baseline (T1), and at one month (T2) and two months (T3) post-randomisation for calculation of QALYs for the cost-effectiveness analysis.

Information about use over the two-month period from randomisation of key health and social services known from published studies to be of relevance to the current population will be collected using a modified version of the Child and Adolescent Service Use Schedule (CA-SUS; Barrett et al., 2012) completed by the parent/carer in order to inform health economic analyses.

Parent mean ratings of Parent Positive using a questionnaire, consisting of three items measuring parents' ratings of the usefulness of each individual zone rated on a 7-point scale (1 = not useful at all to 7 = very useful), which will be summed up to derive an overall app usefulness score. The questionnaire will also capture parents' descriptive and qualitative views of Parent Positive - both positive and negative. This will only be measured among those in the Parent Positive arm.

Usage data will be broken down by Parent Positive zones (Booster, Exchange, Hub). This will allow descriptive analysis of usage patterns. The analysis of the impact of usage levels on the effects of Parent Positive will be based on a derived measure of total time accessing the "Booster" zone during the intervening period. Other app usage metrics will be collected (e.g., engagement in Exchange zone). This will only be measured among those in the Parent Positive arm.

Self-reported standard medical and pre-specified psychological events deemed relevant to the intervention and population group (e.g., increase in detrimental child behaviour, increased family conflict, child protection concerns).