Ecological Momentary Assessment (EMA) studies are distinct in their ability to delve deep into the real-time experiences, moods, and behaviors of participants in their natural environments. If you're setting out on your first EMA endeavor, here are key pointers to ensure a well-structured and ethical approach:
Sampling Frequency Aligned with Study Design
The number of data points captured in a day should be tailored to the study's design and objectives. Just because you can do a lot of sampling, doesn’t mean you should if this will lead to poor adherence and isn’t pertinent to your study aims. Some studies might benefit from frequent sampling, others might require fewer touchpoints. Determine the optimal sampling frequency based on your research questions and the potential burden on participants. Take the time to review the literature to get an understanding of study designs employed by other research groups.
EMA studies permit a flexible approach to survey design. Face-valid questions are most effective and can help keep your surveys short. For example, instead of asking all the items on the PHQ-9, you can ask a couple questions that correlate highly with the PHQ total score, such as “I feel depressed…” “I feel hopeless…”. Adjust questions, where possible, based on dynamic factors such as time, location, or prior responses.
Adherence vs. Participant Burden
Achieving a balance between thorough data collection and minimizing participant fatigue is paramount. As a general rule-of-thumb, shoot for your survey to take no longer than 3 minutes to complete. For multiple surveys in one day, around 1 minute per survey is desirable. Varying the questions over the study period can help keep participants engaged while reducing monotony.
The Nuances of Question Wording
The phrasing of EMA questions can greatly influence responses. For e.g., asking participants "what are you doing right now" vs. "what have you been doing since the last survey (or past hour, etc.)" will impact responses. There is no right or wrong way to word EMA items, but paying close attention to how questions are worded to get to your objectives is important. Ensure your questions align with your study's goals and always pilot-test to gather participant feedback and make necessary refinements.
The sensitive nature of EMA data mandates robust security measures. Always opt for platforms that are HIPAA compliant, ensuring the utmost protection for participant information.
Choice of Platform
Choose between web-based platforms and mobile apps based on the needs of your study and the preferences of your participants. Web-based options allow sending survey links via text, email or Whatsapp, removing the need for app downloads. The web-based approach can be particularly appealing for many clinical populations. However, it does have the disadvantage of requiring a live internet connection, which is an advantage of a native app.
Work by our team member Dr. Raeanne Moore and her colleagues has demonstrated that early adherence to an EMA protocol is predictive of future study adherence (see https://pubmed.ncbi.nlm.nih.gov/34541425/). Therefore, it's crucial to actively monitor survey completion status. One strategy that can help improve overall study adherence is to contact participants during the first couple of days of EMA data collection if they have been missing surveys. Problem-solving why surveys are being missed can help increase adherence for the remainder of the study.
Compensate participants promptly and fairly. Offering small incentives for each survey completed can serve as a continuous motivation and emphasize the appreciation for their contributions to your study.