it_does_follow

Not to mention that the entire class of Markov Chain Monte Carlo techniques only form a subset of general uses for Markov chains.

Markov chains form the basis of n-gram language models, which are still useful today.

Markov chains are also the basis of the Page-rank algorithm.

Hidden Markov Models (which are just an extension of Markov Chains to have unobserved states) are a powerful and commonly used time series model found all over the place in industry.

In the pre-deep learning model Markov chains (and HMMs) in particular had very wide spread usage in Speech processing.

They are probably one of the most practical statistical techniques out there (out side of obvious example like linear models).

Being reputable and being a vanity division are not mutually exclusive.

You could argue that at it's peak Bell labs was a vanity division. That research may have changed the world, but very little of it likely ended up benefiting AT&T in any major way financially. It's telling that once AT&T was broken up Bell labs, while existing in some form for years after, was never reestablished.

My guess is this is ultimately about money.

Facebook/Meta stock lost 30% of it's value a few months back and may not recover any time soon.

Many of these people are high level, so I'm guessing (based on a quick skim of levels.fyi) about 50% or more of their TC comes from stock.

This amounts to an effective 15% pay cut in a year with record inflation.

I think most of us would leave our job over a 15% pay cut, especially if we were well established in the field. On top of this it loosens those golden handcuffs quite a bit for anyone who was on the fence about being employed by facebook, but couldn't say no to the comp.

You've never had to any kind of factor analysis in your work or done any searching for latent variables that map to customer/stakeholder question? Given the number of people I've worked with that are interested in modeling "engagement", I find this hard to believe.

PCA is an incredibly valuable tool that I've used in most jobs I've had. It's just a terrible idea as a default part of a feature engineering pipeline (which is what the author is talking about in terms of "feature selection"), for reasons outline in this article.

I suggest you don't be quite so quick to dismiss important concepts in this area, and before criticizing this post, at least read through it (I noticed your comment about misunderstand what the author is discussing by "feature selection" is the top comment here).

It's very clear if you read the article that what the author is calling "feature selection" might be better termed "feature generation". He explicitly calls out what he means in the post:

> When used for feature selection, data scientists typically regard z^p:=(z_1,…,z_p) as a feature vector than contains fewer and richer representations than the original input x for predicting a target y.

I don't even think this is necessarily incorrect terminology, especially given the author's background of working primarily for Google and the like. It's the difference between considering feature section as "choosing from a list of the provided features" vs "choosing from the set of all possible features". The author's term makes perfect sense given the latter.

PCA is used for this all the time in the field. There have been an astounding number of presentations I've seen where people start with PCA/SVD as the first round of feature transformation. I always ask "why are you doing that?" and the answer is always mumbling with shoulder shrugging.

This is a solid post and I find it odd that you try to dismiss it as either ignorant or click bait, when a quick skim of it dismisses both of these options.

> And I sometimes wonder why.

Numpy.

I honestly think it all boils down to numpy being developed long before matrix libraries became a standard part of software development.

Ruby's early "killer app" (remember that term?) was Rails. Even to this day there is almost no major code out there built in Ruby that isn't ultimately related to building CRUD web apps. While Ruby may be losing popularity now, it moved the web-development ecosystem ahead in the same way that Python has moved the scientific computing world ahead.

20 years ago if you wanted to use open source tools to performant vector code there was Python and a hand full of oss clones of commercial products. Given the Python was also useful for other programming tasks in a way that say Matlab/Octave is not, it was the choice for more sophisticated programmers who wanted an OSS solution and need to do scientific computing. This creates a positive feed back that persists to this day.

Given that Python remains a decent language relative to it's contemporary peers and it has a massive and still growing library of numerical computing software it is extremely unlikely to be dethroned, even by promising new languages like Julia.

Even to this day there is nothing even close to numpy in Ruby. I do DS work in an org that is almost entirely Ruby, but we still use python without question because we know re-implementing all of our numeric code into Ruby would be a fools errand.

Had ruby had early support of matrix math, it wouldn't have surprised me if it would have replaced Python.

I believe the parent is attempting their own demonstration of Poe's law. I was impressed by the quality (and really hope I'm not wrong).

I'm surprised this argument is so hidden in the comments. All things being equal I would prefer permanent standard time, but it's pretty obvious that a very rational way to solve this problem is just choose whichever setting we use the majority of the time.

> That if someone really wants to understand where we are with all those Libya, Syria, Iraq, ... Ukraine.

I appreciate Mearsheimer's perspective, but for a self professed "realist", I find it strange that he talks a lot about "ideology" and very little about "oil".

At the end of the day all of those conflicts are conflicts over the control of fossil fuels. I have a hard time taking any analysis seriously that doesn't focus on this primary issue.

Putin/The Russians aren't insane, they're looking after oil/NG interests. That's the entire reason they captured Crimea in the first place. The Ukrainian government then stopped the flow of water to Crimea to make it basically unusable.

NATO backed oil/NG companies also are annoyed because, despite investing a lot in gas fields in the East and the West, they haven't been able to produce much of anything because the region is under constant military conflict, funded by both the US and Russia.

I agree with the parent comment. If Russia can finally and absolutely control gas fields in the East and have assured access to not only Crimea but water to run the region they'll be getting much more out of this situation than they had prior. They will be interested in stability as much as NATO backed energy companies. Given the conflict in the region, and the recent (2014) overthrow of a government friendly to them (coincidentally right after Shell and Chevron signed contracts to develop gas fields), Russia is, rightfully, as wary of promises from the West as we are of them.

For purely, selfish, greedy reasons Russia would want peace in the region as much as NATO backed oil/gas companies have been hoping for it. There are still gas fields in the West that are waiting to be exploited and already have their resources under contract. Once these resources can be split up in a way everyone can deal with, there won't be conflict until the gas dries up because both parties make tremendously more money with stability after that.

I second this question. In the last few days I've heard pretty heavy reference to "people cheering on nuclear war" but haven't seen it first hand anywhere. A link to an opinion piece that explicitly states this, or even a few high-profile twitter accounts espousing this view would at least convince me it's happening.

Heck, even browsing reddit comments and hacker news comments I've seen no view encouraging nuclear war. Even 4chan doesn't seem to have any posts proclaiming this view.