Many psychologists have not used Ecological Momentary Assessment but are interested in doing so, this guide is for you.
What is EMA?
Ecological Momentary Assessment (EMA) grew out of the earlier Experience Sampling Method (ESM) pioneered by Csikszentmihalyi in his study of Flow. EMS traditionally focused on assessing internal thoughts and feelings while EMA broadens the reach to health, events or people in the person’s environment. ESM and EMA both capture self-report data multiple times a day.
Similar methods include Daily Diary Studies, which present just one assessment a day and Ambulatory Assessment which involves the capturing of some data source other than self-report (e.g. heart rate or movement data).
This guide covers all these methodologies under the umbrella term EMA and more specifically Mobile EMA (mEMA).
Who uses EMA?
EMA is primarily used by psychology and behavioral health researchers and practitioners engaged in a wide variety of fields, including:
- Substance abuse research and treatment
- Smoking cessation
- Eating disorders
- Happiness / Well-being
- Sexual behavior
- Medical disorders
- Time use
- Interpersonal relationships
EMA is also used in these areas to assess the effect of interventions and for clinical outcomes assessment. The same technology is often used for delivering these intervention just-in-time as Ecological Momentary Interventions (EMI).
Market Researchers also use EMA type studies.
Advantages of EMA
EMA holds many advantages over traditional lab or paper-based methods of assessment, including:
- Real-Time: you capture the person’s response to an event at or close to the time it is happening or their internal state as they go about their everyday life, not when they are in an unusual setting such as your lab.
- Over-Time: you capture reports before, during and after the events you are interest it providing more data and an understanding of the processes at work.
- Dynamic Processes: the method allows for modeling of dynamic processes over time rather than simple pre- post comparisons.
- Beyond Self-Report: New technologies allow for the capture of passive, or automatic, data streams such as physiological data, GPS location and environmental factors.
The technology that supports mobile EMA can be divided into three categories:
- SMS / Text message based systems. These systems send participants text messages to which they respond directly. You usually pay a few cents per message so this can be a good option on a low budget. You are however limited to 160 characters per message. There is no ability to use skip logic, answer piping, or to collect any passive data. SMS requires that the phone have cell or WiFi service at the time you want the survey to be completed. You can not restrict when the survey is completed. Companies include Instance Census and Survey Signal.
- Web browser surveys. These system provide a URL the participants opens with the web browser on their phone. The URL may be sent by SMS or email. These surveys allow more flexibility than SMS-based ones but are not designed with a small screen in mind so formatting can be an issue. Costs are mid range (free to ~ $100 per month). The phone must have an internet connection at the time you want the survey completed. Companies include Survey Monkey, Survey Gizmo and Qualtrics.
- Native Smartphone Apps: This is software that runs directly on the phone to provide all the surveys and alerts. It is also capable of capturing passive data from the phone (e.g. location, movement, phone use, light and sound levels, photos, videos, audio files, etc.). Native apps also present multimedia content to participants. It does not require an internet connection so your study keeps running regardless of where the participant is. It is this category of technology that we will cover in-depth in this article.
The disadvantage with this type of approach in the past has been that researchers have had to build an app for each project. Some open source platforms have been made available that make this easier for teams that include programmers but otherwise it can be every expensive to build an app ($10,000 +).
Ilumivu created the mEMA platform which allows researchers to add all their own content (with no programming skills) and re-use the app for multiple project with much lower cost (>$1,195). In addition to ilumivu, companies include ESM Capture, Movisens and Life Data.
When you design, or adapt, an assessment for an EMA study consider the following:
- Keep it short! Experts recommend that the total time burden per day should not be more than 20 minutes
- Utilize skip patterns, branching an answer piping to keep surveys relevant and engaging
- Most EMA platforms will provide a variety of question types including single/multiple selections, visual sliders, scrolling number pickers and free text boxes. Many questions can be presented in multiple formats. Be consistent so that your participants don’t need to think too much, for example, if you have three mood elements you want them to rate you could use continuous sliders (visual analogue scales) for each then switch to a different question type for questions about their current activities.
- Make use of the Smartphone. You can ask participants to submit answers in the form of photos, videos and audio files.
For an in-depth discussion of the differences between traditional and EMA assessments please refer to Trends in Ambulatory Self-Report: The Role of Momentary Experience in Psychosomatic Medicine (Conner, T. & Barrett, L. F., 2013)
Typically four types of alerting or sampling protocols are used in EMA studies:
- Signal contingent: An audio/visual alert is sent by the app when it is time for the participant to complete a survey. The schedule may be purely random or more likely randomized within stratified time blocks (e.g. 1 alert within each 2 hour block from 8am to 6pm)
- Interval contingent: An alert is sent at pre-determined times defined by the amount of time that has passed (e.g. 1 alert every 2 hours beginning at 8am or 1 alert at 9pm each day). This is often used for Daily Diary studies.
- User-initiated event contingent: The participant takes responsibility for completing a survey when the event of interest occurs (e.g. they leave work, they smoke a cigarette).
- Automated event contingent: an alert is sent when the app detects a specified event (e.g. proximity to a location, threshold of motion, heart rate, noise levels, the presence of other participants, etc.).
One of the key advantages of using native Smartphone apps is that they enable you to collect data other than self-report. These alternative data streams can come either from the sensors present in the phone or those in wearable devices. They often include the following:
In-Phone Sensors: Acceleration; Light levels; Noise levels; Screen locked /unlocked; Screen lit / dim; Proximity of others; Open apps; SMS log; Call log; Voicemail log; Web browser log
Wearable Device Sensors: Activity; Sleep; Blood pressure; Heart rate; Heart Rate Variability; Skin conductance; EEG
There are four main ways that EMA / ESM data are likely to be used.
- Create more accurate scores by aggregating an individual’s scores over multiple repeated measures
- Explore how an individual’s patterns change over time
- Investigate within person processes by looking at the sequencing of events and responses
- In the development of an Ecological Momentary Intervention protocol that will send just-in-time alerts or messages to participants in treatment programs.
EMA offers an avenue for capturing unique and highly informative data streams from participants and clinical clients. The mEMA System and other similar platforms have made the methodology much more accessible in recent years and now the technology development is informing new EMA study designs.