mrfredward (u/mrfredward)

mrfredward commented on Using Benford’s Law to Detect Bitcoin Manipulation statmodeling.stat.columbi... · Posted by u/luu

JumpCrisscross · 4 years ago

> the world is full of people who feel very different paying $100.00 vs $99.99

Agree, though that effect is not constrained to Bitcoin. Retail orders, for instance, follow Benford's law. This is despite well-documented psychological biases towards e.g. certain digits, whole numbers, round numbers, et cetera [1]. Benford's law [2] derives from deeper mechanics.

As you point out, however, a better control would have been not all prices in public stocks, but retail orders.

[1] https://mro.massey.ac.nz/bitstream/handle/10179/2695/02_whol...

[2] https://en.wikipedia.org/wiki/Benford's_law#Krieger–Kafri_en...

mrfredward · 4 years ago

Liquid retail stocks follow Benford's law because there is a notion of intrinsic value from the company and an army of quant traders trying to exploit any price inefficiency caused by the retail traders.

With cryptocurrency, the market is less mature and the intrinsic value largely comes from people believing in its value. So really, it would be surprising if we didn't see some Benford's law anomalies associated with people picking numbers.

Anyway, thanks for the discussion; the links above have given me stuff to chew on and calmed the red mist after I got so many drive-by downvotes.

mrfredward commented on Using Benford’s Law to Detect Bitcoin Manipulation statmodeling.stat.columbi... · Posted by u/luu

JumpCrisscross · 4 years ago

> If the author had spent 5 seconds thinking about how markets work

The author has spent a career thinking about this, and has written a good fraction of the textbooks on statistics in market contexts.

mrfredward · 4 years ago

I guess we need to make a distinction between the blog post and the Gary Smith post it links to here.

Gary smith (the person I think you're referring to having spent a career in this) says this:

>The market manipulation, the irrational price gyrations, and the enthusiasm of so many investors for investing in bitcoin (and other cryptocurrencies) is ample evidence that market prices are not invariably equal to intrinsic values.

I entirely agree. A perfectly efficient market should follow Benford's law given enough data.

It's the blog post by Andrew that I think totally misses the point. He leaps from inefficiency which could be market manipulation to this:

>I saw this and I was like, well, yeah, isn’t all bitcoin use either crime or manipulation? But then I realized, no, that’s not all of it. Some bitcoin playas are motivated by politics, some by fomo, some are doing anti-virtue signaling...

And never considers the fact that the world is full of people who feel very different paying $100.00 vs $99.99

mrfredward commented on Using Benford’s Law to Detect Bitcoin Manipulation statmodeling.stat.columbi... · Posted by u/luu

mrfredward · 4 years ago

Benfords law is used to find evidence that the numbers came from a person, not a measurement or mathematical process, right? So anyone who knows what a limit order is should not be surprised to find evidence that humans are involved in picking the prices, right?

It should be obvious that violating Benfords law isn't evidence of fraud or manipulation or even fomo, just evidence that the price is impacted by the people typing in the orders having to pick what number to type in.

Edit: I've softened the language in my comment a bit, but I stand by the fact that this only shows humans are affecting prices, this analysis can't distinguish between fraud and psychological effects around "key" prices, like $10,000.

mrfredward commented on Show HN: Should I Get a House? a better rent vs. buy calculator shouldigetahouse.com/... · Posted by u/alach11

jartelt · 4 years ago

The first several years of the mortgage you are paying mostly interest and not as much towards equity. Plus, you have paid closing costs when you bought, will pay 6% to a realtor when you sell, and have paid property tax and homeowners insurance.

If you sell after 5 years, you are only making money if your home value happened to have gone up. This is by no means a guarantee on a short time frame.

mrfredward · 4 years ago

I am a few months in to a 15 year mortgage after recently refinanced at a 2.125%. Here's a rough breakdown of where each dollar of my last mortgage payment went:

Principal: 60%

Interest: 22%

Escrow(Taxes + Insurance): 18%

And of course the percentage going to interest only goes down with each passing month. The conventional wisdom that you are paying mostly interest in the beginning a) really only applies to 30 year mortgages, and b) was way more true when interest rates were higher. We're currently near some of the lowest interest rates in history, so interest eats a lot less than it used to.

I'll add that I pay a good bit less on my mortgage than it takes to rent an equivalent place in my area. But yes, paying 6% to realtors when you sell is huge, so you still need to own the house a few years for buying to make sense.

mrfredward commented on Boeing discloses a new problem with the 787 Dreamliner edition.cnn.com/2021/07/1... · Posted by u/Ice_cream_suit

kylehotchkiss · 4 years ago

It seems like the manufacturers of these parts aren't producing in bulk, why aren't the tolerances exact and have a min/max? Are they not able to measure the parts out of the factory better? Is the measuring equipment on their end and the gearboxes company difference? Or are these like nanometer tolerances which we just can't manufacture consistently?

mrfredward · 4 years ago

Here's an example for something as simple as a hobbyist using a metal lathe in their garage:

For a rough part, you can measure how much material you need to take off, do it in a few passes without stopping to remeasure, and you're within 5 thousandths of an inch or so.

For a shaft that is going to slide or rotate in a bore without too much force, you need to be within a thousandth or two, so for the last pass you will stop, measure carefully, and only take a little bit of material off at a time so that the cutting forces are low and there is less deflection in the tool to throw off the size of the part.

For a press fit (two parts are sized precisely enough that they can be pressed together with a hydraulic press and then never come apart), you need tolerances in the tenths of a thousandth of an inch. For this, you'll dust off your special expensive micrometer, and it's important to let the part cool before measuring, because the heat from machining can cause the part to expand and cause you to take off too much material, which would ruin the part.

So even for the same person on the same machine with the same material, the effort (and therefore cost, if you're doing this commercially) can vary quite a bit based on the tolerance needed.

I don't know aerospace, but I imagine the required tolerances require vary from "looks good from here" (seats in the cabin) to "must ride on a film of oil this many microns thick when spinning at 10,000 rpm." And the manufacturing processes can be anything from "intern with a saw" to "specialized metrology lab with most expensive machines in the world" depending on what engineering specifies.

mrfredward commented on Dropbox Engineering Career Framework dropbox.github.io/dbx-car... · Posted by u/atg_abhishek

remuskaos · 4 years ago

I feel people who need to be above others, in pay and output, can be verz detrimental to a work environment. Yes, as long as a person contributes to a company functioning, they should be part of its success. And that means getting a raise simply for keeping things running.

I feel the urge to constantly outdo oneself and everybody else tends to burn people out (it has burned out me), and innovation or change just to complete a checkmark on a CV can lead to unnecessary and abandoned projects. Like it happens a lot at Google for example.

mrfredward · 4 years ago

The downside of seniority based pay is that people who show little to no motivation can end up the highest paid on a team if they simply avoid getting in trouble for 20 years.

I know someone who quit a job at Boeing years ago in part because he was at the bottom of the pay ladder doing tons of work while the highest paid non-manager in his department didn't do anything except keep the printers stocked with paper.

Throwing incentives on competitive people can be toxic, but the opposite problem is that when high performers don't get rewarded the organization will rot.

mrfredward commented on NDA expired, let’s spill the beans on a weird startup shkspr.mobi/blog/2021/07/... · Posted by u/pimterry

eropple · 4 years ago

Has he confused them? The only code of professional ethics in this industry I've ever been asked to consider is the ACM one. https://www.acm.org/code-of-ethics

By my reading of it, I'd feel obligated to publicly address this, and I don't consider it a breach of any sort of ethics I'd believe in, besides.

mrfredward · 4 years ago

From the code you linked:

> Computing professionals should protect confidentiality except in cases where it is evidence of the violation of law, of organizational regulations, or of the Code. In these cases, the nature or contents of that information should not be disclosed except to appropriate authorities.

mrfredward commented on NDA expired, let’s spill the beans on a weird startup shkspr.mobi/blog/2021/07/... · Posted by u/pimterry

_game_of_life · 4 years ago

>You've confused ethics and morals

Ethics and moral philosophy are synonymous. I don't think they're confused, but you can consult a dictionary if you like.

>The ethical action (which is about professional standards rather than your conscience)

No, as somebody who has studied moral philosophy academically, this is your own unique definition and not normal. Any amount of research from a credible source like plato.standord.edu or even wikipedia will support this.

mrfredward · 4 years ago

The dictionary defines ethics as the field of knowledge dealing with moral principles, sure, and that's not at all what I'm talking about here. Perhaps I erred in using the word too generally and should have been specific in talking about ethics in the professional sense.

The ethical codes that are associated with a profession are different from moral principles that may usually guide us. The first example they gave when I studied this in engineering was that of a defense attorney: trying to help a guilty person get away with a serious crime violates most people's moral standards, but the code of ethics for attorneys demands that they defend guilty people anyway, because our law system is set up with that expectation.

To my original point, someone may claim a moral imperative to tell the world about the company in this article, but the fact of the matter is just about every professional ethics committee or handbook would tell you to uphold your NDA in the situation here. Wasting people's time under false pretenses may be bad, and it isn't ethical to do it yourself, but it isn't so bad that you can just drop your own obligations and blog about it.

And yes I admit some handwaving here since programming doesn't have widely adopted ethical codes yet, but I can guarantee that when they do exist, they won't tell you to violate a contract for something that won't injure anyone and doesn't break any laws.

mrfredward commented on NDA expired, let’s spill the beans on a weird startup shkspr.mobi/blog/2021/07/... · Posted by u/pimterry

bluGill · 4 years ago

It is also unethical to abide by a NDA if the company is doing something unethical. It might or might not also be legal to talk though, ask a lawyer. Of course NDAs might not even be legal in the first place. If the company is doing something illegal, then the NDA doesn't have any meaning for sure.

mrfredward · 4 years ago

You've confused ethics and morals. The ethical action (which is about professional standards rather than your conscience) is usually to follow the legal agreement you've signed (barring something that supersedes the NDA like being legally required to report something to regulators).

So no, it isn't unethical for the author to abide by his NDA, arguably the exact opposite is true, though exposing these shenanigans at a personal risk could be argued to be the better moral decision.

mrfredward commented on Copilot regurgitating Quake code, including sweary comments twitter.com/mitsuhiko/sta... · Posted by u/bencollier49

stefan_ · 4 years ago

Even includes the commented out code. Clearly Copilot has gained a deep understanding of code and is not simply the slowest way to make a terrible, opaque search engine ever!

mrfredward · 4 years ago

From the tweet it looks like an awesome search feature. Just type what you wanted to search for right inline and then it can drop the result in without you ever changing a window or moving a hand to the mouse.

Problem is you don't know whose code you're stealing, which leads to all sorts of legal, security, and correctness issues.