Effective participant recruitment is one of the most critical factors in determining the success of a research study. A well-planned recruitment strategy not only helps you reach your target sample size but also ensures that participants remain engaged throughout the study period. In this article, we share evidence-based recommendations for recruitment periods, invitation frequencies, and notification schedules that can help maximize your enrollment rates while maintaining participant engagement.
Recommended Recruitment Period
The duration of your recruitment period should be tailored to your study’s specific circumstances and participant pool. We recommend a shorter, more intensive recruitment period if you have a defined list of potential participants. This approach creates a sense of momentum and urgency, which can significantly improve response rates.
For studies recruiting from a broader, undefined population (e.g., via social media or public announcements), the recruitment period may need to be longer and more opportunistic. However, it’s important to note that most of your enrollments will likely come within the first 72 hours of the initial invitation push. A defined recruitment window helps in planning subsequent study phases and ensures that your team can focus on participant engagement once enrollment begins.
When setting up your study in Avicenna, you can configure the Participation Period to align with your recruitment timeline. This ensures that participants who join during your recruitment window have a clear understanding of their expected participation duration.
Recommended Invitation Frequency and Schedule
Finding the right balance in invitation frequency is crucial. Too few invitations may result in missed opportunities, while too many can lead to “list fatigue,” where potential participants either ignore all messages or mark them as spam.
We find a pattern of 3 total invitations to be the most effective balance. More than 4 invitations can lead to diminishing returns with each subsequent message. The first email will yield the most sign-ups, the second will capture a smaller group who were busy or undecided, and the third serves as a final “last chance” prompt.
Recommended Invitation Schedule
A common and effective schedule for sending invitations is:
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Invitation 1 (Day 0): Initial contact. This is your primary invitation and should be clear, compelling, and include all necessary information about the study.
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Invitation 2 (Day 2 or 3): First follow-up. This short delay is effective for those who saw the first email but didn’t have time to act on it. The message should acknowledge that they may have missed the initial invitation and provide a gentle reminder.
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Invitation 3 (Day 6 or 7): Final, friendly follow-up. A longer delay here prevents the feeling of being spammed and serves as a final reminder before the recruitment window closes.
When inviting participants in Avicenna, you can use the Invite Participants feature on the Participation page. This allows you to send invitations via email, and you can customize the invitation message using Notification Templates. For invitation-based studies, you can track pending invitations using the Pending Invitations tab to monitor your recruitment progress.
Recommended Notification and Reminder Schedules for Activities
Once participants have joined your study, maintaining their engagement through well-timed notifications and reminders is essential. The goal is to provide helpful nudges without causing “notification fatigue,” which can lead to participants ignoring all prompts.
For an activity with a defined completion window, a combination of an initial notification plus 2-3 reminders is highly effective. This strategy covers participants who respond immediately, those who need a mid-window nudge, and those who respond just before a deadline.
It’s important to note that participant response patterns often cluster at two points: immediately after the first notification and right before the activity expires. Your reminder strategy should support these natural behaviors.
Recommended Schedule for a 6-Hour Activity Window
For activities with a 6-hour completion window, we recommend the following notification schedule:
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Notification 1 (Time: 0 minutes): Sent the moment the activity is released. This is the primary prompt and should clearly communicate what the participant needs to do.
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Reminder 1 (Time: +2 or +3 hours): A mid-point reminder. This catches participants who were busy when the first notification arrived and provides a helpful nudge at a natural break point.
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Reminder 2 (Time: +5 hours, i.e., 1 hour before expiry): A “final reminder” that creates a sense of urgency and is very effective for boosting completion rates among those who may have forgotten.
You can implement this notification strategy in Avicenna by creating multiple Notification Templates for each activity. When creating a notification template, you can set the Offset to control when the notification is sent relative to the triggering event. For example, you can create:
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A notification template that triggers on
Session Releasedwith an offset of 0 minutes (immediate notification) -
A reminder template that triggers on
Session Releasedwith an offset of +2 or +3 hours (mid-point reminder) -
A final reminder template that triggers on
Session Releasedwith an offset of +5 hours (final reminder)
Note: For more details on creating and configuring notification templates, please refer to the Notifications documentation.
Best Practices
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Plan your recruitment timeline: Define your recruitment window before you begin, and communicate this clearly to your team. This helps create momentum and allows for better resource planning.
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Personalize your invitations: Use participants’ names when possible, and ensure your invitation messages are clear about the study’s purpose and what participation entails. You can customize invitation emails using Notification Templates with the
Study Invitationevent type. -
Monitor your recruitment progress: Use the Participation page to track enrollment rates and identify any issues early. The Pending Invitations tab is particularly useful for monitoring who has been invited but hasn’t yet joined.
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Respect participant preferences: Some participants may prefer fewer notifications. Consider allowing participants to customize their notification preferences, as discussed in How to Set Reminders Based on Participants Preferences.
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Test your notification schedule: Before launching your study, test your notification templates to ensure they’re working as expected. You can do this by creating test participants and monitoring when notifications are sent.