Articles

Introducing longitudinal projects on Prolific: A dedicated way to run longitudinal studies online

Lily Haycraft Mee

|May 28, 2026

Introducing longitudinal projects on Prolific

Longitudinal studies are among the most valuable designs in behavioral research. They let you track how people change over time (across days, weeks, months, or years) in ways no single-session study can. They're also historically among the hardest to pull off.

Until now, running online longitudinal studies on Prolific has been possible, but required a level of ingenuity that shouldn't be necessary. A six-wave diary study meant creating six separate studies by hand, building allowlists or participant groups between each one, tracking attrition in spreadsheets, and calculating costs yourself.

Today, we’re making this much easier by introducing longitudinal projects. This new approach brings everything into a single, structured workflow, making it easier to design, launch, and manage multi-wave research from start to finish.

The problem with longitudinal research isn't just participant retention, but everything around it

When researchers discuss the challenges of longitudinal studies, retention is often the first to come up. You're asking participants to return regularly, managing drop-off across multiple waves, and hoping the sample you end up with looks like the one you started with.

Attrition matters. Getting an incomplete dataset reduces sample size and statistical power. Plus, if the people who drop out of your study are systematically different from those who stay, your data no longer represents what you think it does. Attrition isn't just an operational inconvenience, but a validity threat.

But retention is actually a downstream problem. The upstream problem is that running a multi-wave study online has required researchers to do many tasks manually that a longitudinal study platform should handle automatically: sequencing waves, controlling who can access each wave, forecasting how many participants you'll actually need, and monitoring drop-off in real time before it compromises your final dataset.

That's why we've built longitudinal projects: to give you the longitudinal research tools you need.

What’s new: A simpler way to run online longitudinal studies with Prolific

Set up your waves once, and let participants run through

With longitudinal projects, your entire multi-wave study lives in one place. You define your target audience and screening criteria once at the project level. These then apply consistently across every wave, so you're tracking the same participants throughout.

Set your total number of waves, schedule when each one goes live, and Prolific handles sequencing automatically. Participants can access each new wave only after completing the previous one, with no risk of skipping ahead or entering mid-study. Your dataset stays clean and complete from wave one to the last.

It’s flexible too. If you’re not ready to set up and schedule all waves upfront, just create placeholder drafts. Then you can fill in the final details and schedule each one when ready.

Creating multiple waves for a longitudinal study

Forecast your costs and retention before you launch

One of the most frustrating parts of running longitudinal research has been not knowing what you're in for until you're already in it. How many participants do you need to recruit in wave one if you want 200 completions at the end? What does drop-off actually cost you, wave by wave?

Longitudinal projects include a built-in retention and cost calculator. Enter your target final sample size and your anticipated retention rate, and Prolific will calculate the number of participants you need to recruit upfront to reach your goal. You'll see projected drop-off per wave and a full cost breakdown for each wave. Adjust your inputs to model different scenarios and plan your budget with confidence.

If you’re not sure how to predict retention rate, we recommend running a small pilot to accurately test for participant attrition within your specific study setup. Alternatively, you can look for similar study designs in research literature to get a benchmark, or you can refer to retention estimates in our paper on retention in online longitudinal studies.

Track and manage participant attrition in real-time

Even well-designed longitudinal studies can fall behind. Prolific’s longitudinal projects give you a live retention dashboard showing actual versus forecasted drop-off as your study runs. If your numbers start drifting from your target, you'll get an early warning in-app. We’ll give you a clear picture of the projected impact on your final wave count.

Crucially, you can act on it. Message participants with reminders, or open up additional places in earlier waves to get back on track. You stay in control throughout the study, not just at the start.

Prolific’s own research scientists have also provided lots of tips on how to improve retention of participants across studies. Read them here to maximize retention. These tips have helped researchers on Prolific achieve stats such as 90% retention with 300 participants over 30 days.

Participants know exactly what they're signing up for

Retention doesn't only depend on what you do as a researcher; it also depends on how much participants understand what they're committing to. With longitudinal projects, participants can see the full study schedule upfront: every wave, the time commitment for each, the payment, and when each one opens. If you haven’t set up the details for later waves or scheduled them, participants will still see that another wave with more details is coming soon.

When participants have a clear picture of what's involved before they start, they're better positioned to commit. And participants who commit are participants who return.

Participants can see the whole study schedule

What researchers have already achieved on Prolific

Longitudinal studies on Prolific have a strong track record even before this feature existed. Researchers have achieved results such as:

All through approaches that required significant manual effort to set up.

Longitudinal projects are designed to make results like these more achievable and consistent for everyone, not just those with the time and technical inclination to build their own systems around the platform.