Experimental School Choice with Parents
This paper presents the first laboratory school choice experiment using parents as subjects, finding that while all mechanisms are frequently manipulated with similar truth-telling rates, the classic tradeoff between stability and efficiency persists: Deferred Acceptance ensures stability but lacks efficiency, whereas the Rank-Minimizing mechanism boosts efficiency at the cost of increased justified envy, with Efficiency-Adjusted Deferred Acceptance offering a modest middle ground.
Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine you are a parent trying to get your child into the best local school. You have to fill out a form listing your favorite schools in order. But here's the catch: you don't know exactly how many spots are open, who else is applying, or how the computer decides who gets in. You might be tempted to lie on your form—maybe you put a "safety" school first just to be sure, or you skip a popular school you think you can't get into, hoping the system will be smarter than you.
This paper is a giant, real-life experiment to see if parents actually behave like the students (university undergraduates) that economists usually test in labs. The researchers wanted to know: Do real parents play the game differently than college students? And does the computer system we use to assign kids to schools actually protect them if they try to game the system?
Here is the breakdown of the study using simple analogies.
The Three "Game Rules" (Mechanisms)
The researchers tested three different ways to assign students to schools. Think of these as three different rulebooks for a game:
The "Honesty is Best" Rule (Deferred Acceptance - DA):
- How it works: This is the current standard in many places. The rulebook says, "Just tell us your true favorites. If you lie, you can't possibly get a better result, and you might get a worse one."
- The Theory: It's supposed to be a "safe" game where you never need to strategize.
- The Reality: Even though the rules say "just be honest," people still tried to trick the system.
The "Efficiency Booster" Rule (EADA):
- How it works: This is a newer, more complex rule. It tries to fix the "wasted spots" that happen in the first rule. It's like a referee who says, "If a student is holding a spot they don't really want, let's swap them to make everyone happier."
- The Theory: It should give better results than the first rule, but it's harder to understand.
- The Reality: It was supposed to be a middle ground, but in the experiment, it ended up causing more confusion and "unfairness" (envy) without really making things much better.
The "Rank Minimizer" Rule (RM):
- How it works: This rule ignores who has "priority" (like living near the school) and just tries to give everyone the highest possible rank on their list. It's like a lottery that only cares about your happiness, not the rules of the neighborhood.
- The Theory: This should give the absolute best results for everyone's happiness.
- The Reality: It did give better results, but it broke the "fairness" rules, meaning many kids got into schools they didn't prioritize, while kids who did prioritize them got shut out. This creates "justified envy" (anger that the system wasn't fair).
The Big Discovery: Parents vs. Students
The researchers recruited 324 parents and 216 students to play these games in a lab. They gave the parents real money (up to £55) to make it feel like a real school choice.
1. Everyone Lies (or tries to)
The biggest surprise? Parents lied just as much as students.
- The Myth: We thought parents, being more experienced and mature, would just follow the rules and tell the truth.
- The Truth: Only about 26% of parents told the truth under the "Honesty" rule. The rest tried to game the system.
- The Analogy: It's like a traffic light. Even if the sign says "Stop," some people still try to run the red light. It doesn't matter if you are a 22-year-old student or a 43-year-old parent; when the stakes are high, people try to find a shortcut.
2. The Type of Lying is Different
While the amount of lying was the same, the quality was different.
- Students: They made silly mistakes. They would put a school they hated at the top just because they didn't understand the game. It was like a child trying to solve a puzzle and putting the square peg in the round hole.
- Parents: They made deliberate mistakes. They understood the rules but chose to lie anyway, thinking it would help them. It was like a chess player making a risky move.
- The Lesson: Parents aren't "dumber" than students; they are just more strategic. But being strategic didn't help them; it often hurt them.
The "Sophistication Trap"
Here is the most interesting part about smart people.
- The researchers measured how "smart" the participants were using logic puzzles (Raven's Matrices).
- Under the "Honesty" Rule (DA): Being smart didn't help you get a better school. In fact, the smartest people tried to lie the most, but since the system is designed to punish liars, they ended up with the same result as everyone else.
- Under the "Efficiency" Rule (EADA): Being smart backfired! The smartest people tried to outsmart the system, and because the system was tricky, they ended up with the worst schools.
- The Analogy: Imagine a maze.
- DA is a maze where if you try to run the walls, you hit a dead end. It doesn't matter how fast you run; you end up in the same spot.
- EADA is a maze with hidden traps. The people who think they are the fastest runners (the smartest) try to sprint through the shortcuts, but they fall into the traps and get stuck. The people who just walked slowly and followed the path (told the truth) actually did better.
The Final Verdict: Why "Honesty" Still Wins
Even though everyone tried to cheat, the "Honesty" rule (DA) turned out to be the best protector for families.
- DA: It's not perfect (it doesn't always get the absolute best school for everyone), but it is safe. If you lie, you won't get a better spot, and you probably won't get a worse one either. It's like a seatbelt: it doesn't make the car go faster, but it keeps you safe if you crash.
- EADA: It promised to be a "better" car, but it turned out to be a car with a confusing dashboard. It made people try to drive faster, but they crashed more often.
- RM: It was a race car. It got you to the finish line faster (better schools), but it had no brakes and no seatbelts. Half the drivers ended up in the ditch (unfairness/jealousy).
The Takeaway for Policymakers
The study concludes that we shouldn't worry about parents being "too smart" for the system.
- Parents behave similarly to students in terms of how often they try to cheat.
- However, because parents are more deliberate in their cheating, they are more likely to hurt themselves if the system is complex.
- The Best Policy: Stick with the "Honesty" rule (DA). It doesn't rely on parents being perfect or honest. It relies on the system being robust. It ensures that even if a parent tries to game the system, they won't lose out. It levels the playing field not by forcing truth, but by making lies useless.
In short: The system that asks you to be honest is the only one that actually protects you when you decide to be tricky.
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