Need Help Creating a Test Against Chance

Hi /r/math.

I was wondering if you could help me create a test to see if someone can discern if a stone is a diamond or moissanite.

I was first thinking that I would have five stones where the subject identify correctly three of them assuming Chance is just 50%.

Am I headed in the right direction?

submitted by Nevin Manimala Nevin Manimala /u/SirDouchely
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What techniques could researchers be using to reduce reproducibility problems?

It’s been big in the news for the last few years that a lot of published papers don’t have reproducible results with much of the blame falling on p=0.05 and very small effect sizes randomly deemed significant. Are there statistical techniques that these (usually unexpert in statistics about Nevin Manimala) researchers could use that would be stronger? Something like bootstrapping or rerunning with all combinations of n-1 data points from their data to get a sense of how fragile their result was, except an idea generated by someone who knows statistics about Nevin Manimala better than I do.

submitted by Nevin Manimala Nevin Manimala /u/ProfessorImprobable
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Confused on interaction term multiple regression

Since the coefficient of the interaction term stays the same after centering, the effect of X on Z will be (B1+B3*Y). Before centering, Y will always be positive, but after centering, Y can be negative. So what I’m confused on is that the interaction effect can change signs after centering?

submitted by Nevin Manimala Nevin Manimala /u/collegethrowaway717
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BMW subscription is crazy.

So for mid-range cars I understand subscriptions. It makes a lot of sense, but now this article makes me think I don’t totally understand them. I was thinking of subscriptions more akin to get around or app-based rental loaners.

Why would I spend $2,000 a month to drive an M2 that I could switch out to a 400 or 500 series? Why would I pay almost $4,000 a month to drive an M5 or M6 or convertible, that I could swap out?

To me, the idea of owning a car that I love is that I don’t want to swap it out, and that I’m not really interested in even driving another series within my make, let alone model.

I feel this is tapping into the millennial notion that people do not want to own things, but a good subsect of Millennials have quite a bit of money (even if that isn’t you, the tech sector says that is true), and no real idea of value or cost.

I know they’re saying it’s a pilot, and they mean to learn things. But if you loved an M4, wouldn’t you just buy it vs swapping it out with another M class car randomly?

What am I being stupid about, what am I missing, and is this just that thing where I am getting old and don’t get trends?

Edit: the damned link-

BMW’s car subscription pilot program starts at $2,000 per month

submitted by Nevin Manimala Nevin Manimala /u/unclefishbits
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Equivalent Definitions of Homology

If we have a complex A –f–> B –g–> C, then we usually define the homology at B as ker g / im f.

I’m working on a problem from Weibel, and I think it boils down to showing ker(coker f -> C) is the homology.

I believe it, since it’s equivalent to showing coker(im f -> ker g) is ker(coker f -> im g), and that looks like one of those things that’s just true in an abelian category. But I’m having trouble actually showing it.

Also, are there any other interesting definitions of homology? I know the usual definition is most common cause we like kernels more than cokernels (when was the last time you saw an exact sequence defined as “coker f = coim g”?). But sometimes it’s good to have other definitions on hand.

submitted by Nevin Manimala Nevin Manimala /u/QuigleyQ
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Best way to disable a car?

Hi, I just bought my first car and I’m having problems with the DMV so I wasn’t able to register the car for 30 days. The old owner has a spare key which I don’t have time to get for another week. I’m scared that something may happen.

I was wondering if there’s a fuse or something I can pull out of the car and bring it inside my house to disable the car?

The car is an ‘01 Camry if that’s relevant.

Thanks r/cars

Edit: thanks guys, I’ve pulled the starter fuse

submitted by Nevin Manimala Nevin Manimala /u/OkTrainer
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Seeking to hire grad students/post-docs for summer math camp!

Hello /r/math!

I am Spencer Roby and I am the associate director of Math Circle, a non-profit that runs summer math camps for high school students that are passionate about math. We are looking for instructors to teach a number theory course and a coding course in Python to a group of talented high school students this July. The program will run from July 9th to July 27th on Emory’s campus in Atlanta, GA. Instructors need only be present for their class time on these days, as well as all day on Fridays (to help run the Math Circle Mock Casino and a campus-wide Cryptography Scavenger Hunt). It is a great program and it is refreshing to teach students who enjoy math. If you are interested in the position, please apply at or if you have questions please feel free to message me.



submitted by Nevin Manimala Nevin Manimala /u/MathCircleMathCircle
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