In Simple Words
Assigning people based on their birthdate works like splitting a crowd into two equal groups based on whether their ticket number is odd or even. Because birthdays are evenly distributed across the population, everyone born in the first half of the month gets one treatment and those born in the second half get another, creating two balanced groups without bias.
Research question
Field experiments in public administration often face ethical and logistically complex barriers when assigning individuals randomly to social policies.
Participants
N = 5,180 total inflow individuals (human, Denmark: Storstrøm and Southern Jutland counties).
Study Design
Randomized Controlled Trial assigning individuals born on days 1–15 to treatment and days 16–31 to control.
Results
Produced balanced baseline demographic distributions across treatment and control groups while enabling evaluation of policy regime shifts.
Takeaway
Assign social trial participants using birthdate splits (1st–15th vs. 16th–31st) to implement transparent, unmanipulable field randomization.
Source and citation
See source →Read alongside the research
Plain-English glossary
Original explanations, informed by the references below. Examples are illustrations, not data from the studies above. The research text stays unchanged.
- Baseline
The starting measurements in a study. Researchers use these to compare what participants were like at the start with what happens later.
ExampleBefore a training programme starts, researchers measure workers’ earnings. That first measurement is the baseline.
GET-IT glossary · Baseline characteristics ↗Read more about baseline →