The math of school lotteries

Reply #9

cottoneyedjoe — Tue, 22 Nov 2022 17:19:38 GMT

I agree with you about sibling preference being important, at least when children are elementary aged. I started thinking about this topic of school lotteries after a conversation with a friend whose grandchild was applying for a spot in a public magnet school or charter school lottery. They were complaining that the school had set aside a fixed number of spots for applicants who lived in the neighborhood, and that it was unfair because people could game the system by renting a small apartment a... [ More ]

Reply #8

Stack47 — Tue, 22 Nov 2022 08:12:38 GMT

The Warriors started tanking early this season.

Reply #7

db101 — Tue, 22 Nov 2022 01:21:32 GMT

Actually I might have to take that back. I'm aware of sibling preference in admissions. Unfair, yeah, but justified. It would be worse to foster jealousy and resentment in the home. Can you imagine if someone had twins and one got a spot thru the lottery and the other didn't, and the parents sent one to the good school and the other to the crappy school? I think if you didn't manage to beg for a second spot the only option would be to send both to the crappy school.

Reply #6

cottoneyedjoe — Mon, 21 Nov 2022 16:50:18 GMT

I don't disagree with you. It can be a touchy issue. These policies are usually set by local school boards, so it might give you something to think about next time you're deciding which ones to vote for.

Reply #5

db101 — Mon, 21 Nov 2022 14:54:56 GMT

Not sure I can support a public charter or public magnet school having so many reserved spots in a lottery and tbh I didnt even know it was a thing. Your faculty example is borderline iffy, but I can see the justification if the Uni partly funds the school. And children of professors are probably better students academically.

I'd draw the line at reserving spots for students with characteristics they cant control, like their race or how much money their parents make.

Reply #4

cottoneyedjoe — Sun, 20 Nov 2022 17:37:03 GMT

You're probably right about two simple drawings being easier to administer than one drawing with complicated weights. I got the same expected value when I took random samples, and it wasn't intuitive at first how to even simulate a drawing with non-integer weights on some entries. The key is to take out all of an applicant's entries if one of their entries is picked because you can't have the same applicant picked twice. Not sure how you set yours up, but what I did was pick a random number over... [ More ]

Reply #3

db101 — Sun, 20 Nov 2022 15:52:32 GMT

Man I'm glad I don't have young kids anymore. Remember how simple it was in the old days when you either sent your kids to the closest neighborhood public school or the Catholic school?

I ran simulations of your weighted drawing and the average number of faculty kids was about 8.89. I didnt expext it to be more than 1 kid fewer, so that is interesting. The average must be lower because the single drawing set up has the possibility of no faculty kids being selected.

If you're faculty, you... [ More ]

Reply #2

cottoneyedjoe — Sun, 20 Nov 2022 05:12:15 GMT

Yeah, and how to solve the problem of intentionally tanking.

Reply #1

Stack47 — Sat, 19 Nov 2022 04:34:22 GMT

Hopefully after this question is answered someone can explain the NBA draft lottery .

The math of school lotteries

cottoneyedjoe — Thu, 17 Nov 2022 21:16:41 GMT

This topic might be familiar to some depending on your kids' ages and the school options in your area.

Scenario A: Suppose a magnet school or special program has 100 spots open and students will be selected by a lottery. Say there are 2500 kids who are eligible for the lottery. With simple math, it's easy to see that each kid's chance of getting selected is 100/2500 = 4%.

Scenario B: There are still 100 spots open and 2500 eligible kids, but with a hitch. The school is partly supported... [ More ]