Table 3.

mHealth evidence reporting and assessment (mERA) checklist.

Criterium	Explanation
1. Infrastructure	Participants/patients need a smartphone (iOS or Android) with active internet connection. Researchers/clinicians need a computer with internet access to create and schedule EMA or EMI interactions, and to visualize and analyse results in the online dashboard.
2. Technology platform	m-Path is a closed-source EMA and EMI platform, that relies on Firebase Cloud Messaging for computer-phone communication. The mobile app is designed in Flutter, the online dashboard in HTML, CSS and JavaScript. The server side interface with the MySQL database is written in PHP. The continuously running process that tracks all schedules and sends push notifications using Firebase Cloud Messaging is written in Julia.
3. Interoperability	API-based interoperability connections can be developed to interact with other care systems or electronic health records.
4. Interaction delivery	EMA or EMI interactions can be scheduled a priori and sent in a notification-based manner or user-initiated. Collected data may consist of active self-reports (text responses, numerical ratings, photos, voice recordings), passive mobile sensing logs (see Table 2 for specifics), and/or meta-information (reaction times, skipped items, presentation order).
5. Interaction content	m-Path only enables communication between participants/patients and researchers/clinicians. The actual content and responses are provided by the users of our platform. All created materials can be stored locally, shared with others privately or publicly via the public m-Path library.
6. Usability testing	The input from various self-created UX surveys, think aloud protocols, and qualitative interviews was used to develop and improve the usability of our online dashboard.
7. User feedback	A self-conducted survey among our dashboard users indicated that they would highly recommend m-Path to others (6.37 on a scale from 1 to 7).
8. Access of individual participants	Any owner of an iOS or Android device can install our mobile app, except for participants/patients with a recent Huawei phone. Active mobile internet or Wi-Fi is required to receive notifications or to upload responses to the server. m-Path supports various accessibility features for those with visual or cognitive impairments (e.g., audio assistance, increased font sizes, smiley ratings or image choice items, etc.).
9. Costs	In its basic form, m-Path is currently free to use. To make use of premium features (e.g., automation, advanced data exports, priority support, etc.), an annual subscription fee is requested (see www.m-path.io/landing/pricing/ for an up-to-date pricing page). All revenues are used for further development, system maintenance and support, and legal consultancy.
10. Programme entry	Anyone who registers with a valid email-address can make a researcher/clinician account to set up an EMA or EMI study in the web-based dashboard. Participants/patients need a study/clinician connection before they can take part in a specific EMA or EMI protocol (either via manual lookup or invitation code).
11. Conditions for delivery at scale	Our servers only process and store text-based data. This requires minimal working and long-term storage capacity, which allows us to effectively scale up our system when the user base or traffic on our platform grows.
12. Contextual adaptability	Our software allows for highly tailorable and versatile EMA and EMI designs in terms of item content, survey flow and notification set-up. Unsupported features or functionalities can be developed against a development cost. The app is available in more than 15 languages.
13. Replicability and documentation	There is an online manual with up-to-date software documentation (see www.m-Path.io/manual) and a moderated help centre (see http://www.reddit.com/r/mpath).
14. Data security	Identifiable participant/patient information is not required to register to the mobile app. Server-phone communication is end-to-end encrypted. m-Path's source code is obfuscated, limiting the exploitation of unforeseen vulnerabilities. Researcher/clinicians accounts are supplied with two-factor authentication. Physical servers are only accessible by maintenance personnel.
15. Compliance with national guidelines	m-Path complies with the European Union's GDPR policy, one of the strictest privacy policies applied in the world, meaning that participants have full control over their data. The prerequisites for medical device certification are being investigated.
16. Fidelity of intervention	Various real-time graphs in the online dashboard visualize participants’/patients’ responses and engagement (e.g., compliance rates). Adherence can be boosted via our award system (e.g., gamification).