Comments on FiveThirtyEight: Politics Done Right: Hooray! The Second Derivative of the Unemployment...

Boing said... Christ. is that the best you ca...

2009-05-09T21:39:00.000-04:00

Boing said...

Christ. is that the best you can do? Using quantum physics to refute someone's claim that time is continuous in economic theory?

And spelling "Planck" wrong while you're at it... ;

Knew I'd leave something for someone to pedantically correct my pedantic correction of someone's pedantic ... well, you see where this is going :)

I haven't posted in a long time here, mostly becau...

2009-05-09T18:05:00.000-04:00

I haven't posted in a long time here, mostly because of my lack of expertise, but since this is largely about mathematics, something I understand, I thought I'd chime in with my opinion.

The second derivative is technically the rate of change of the rate of change, and can only be computed using continuous functions. Hence Nate is "wrong." But some posters here have claimed that this term is used for the second discrete derivative, not something I've heard about. Nonetheless, I don't blame Nate for using this term, since I instantly understood what he meant. The purpose of his posts is communication, and since he successfully communicated, no fault lies with this minor misuse of language. It's better than saying the "change of the change," in my opinion.

However, I think the title should be something like "hooray, the second derivative is good!" Positive is good. To clarify, if there are enough jobs for everyone, that's saying the zeroth derivative of jobs is good. If there aren't enough jobs for everyone, but there are more jobs than there used to be, then you can say the number of jobs has improved, or you can say that the first derivative is good. What we have instead is a situation where the first derivative has improved, or the second derivative is good.

Although my work is more likely to involve actual derivatives than differences, I will comment that it is difficult to extract accurate derivatives from noisy data. In this case, there may be many short-term fluctuations that cause small changes in employment. By taking differences, and differences of differences, one is likely to see spurious fluctuations in the second derivative that are virtually meaningless. This may be the reason there have historically been so many "false starts." For this reason, it is HIGHLY adivsable to do SOME sort of smoothing before trying to draw conclusions. A single blip by this arbitrary measure is hard to interpret as anything.

WV - groph - we are trying to groph every smidgen of good news from this economic data.

Prag- The terminology Fox News is using is,unfort...

2009-05-09T14:44:00.000-04:00

Prag-

The terminology Fox News is using is,unfortunately,correct.The unemployment rate did increase.It was the job loss rate that decreased.Big difference.

"Horray! The Second Derivative of the Unemployment...

2009-05-09T14:41:00.000-04:00

"Horray! The Second Derivative of the Unemployment Rate Improved!"

Second derivative? Huh? Nate don't you know Physics from Calculus? The "Unemployment Rate" is a term of velocity. The rate of change in the "Unemployment Rate" is a term of acceleration.

In proper English your headline should have read: "Hurray! The Acceleration of the Unemployment Rate Finally Decreased!"

I have maintained a very healthy skepticism about ...

2009-05-09T14:25:00.000-04:00

I have maintained a very healthy skepticism about all the "green shoots" being reported about the economy in recent months. It seems a lot of this is "down so far it feels like up," because the months of August-September were so disastrous, both for GDP and employment.

It's like all the positivity about the recent "bull(sh*t) market" that has seen a 35% increase in 2 months...while conveniently leaving out that it's still down 30% from 1 year ago. People are still overindebted without real wage growth (check the stats on the large number of people forced to work part-time instead of full-time), and until that starts to change over, this recovery is cosmetic only.

And we're not even bringing up the huge amount of cutbacks and layoffs that will be happening in the public sector in the next 6 months. Wait till those show up in the stats and reverse the recent gains in government payrolls.

Now imagine imagine if Gramps and Mooseburger were trying to solve this. Thank God this country chose wisely last November.

Today's Flight From Reality Journalism... Of all...

2009-05-09T14:02:00.000-04:00

Today's Flight From Reality Journalism...

Of all who read yesterday’s unemployment figures only Fox News thinks the rate is still rising…

If the inflection point continues to improve throu...

2009-05-09T13:36:00.000-04:00

If the inflection point continues to improve through the summer, then their will be cause for optimism.

*************

Ass Rider's stench is the same no matter what his handle is.

**************
This discussion shows how a small amount of math knowledge is a dangerous thing.

All of the grammar Nazis can get bent too.

Erm... as I understand it, in terms of differentia...

2009-05-09T12:11:00.000-04:00

Erm... as I understand it, in terms of differentiation of an equation, the first derivative (dy/dx) is the gradient, or 'how quickly you're losing jobs'. The second derivate (d^2y/dx^2) is 'how fast is the rate of change changing?' Nate is therefore more or less correct, and so the worsening of the situation is not as bad as it was (if that makes any sense at all), although of course, he's using the wrong terminology.

Of course, once the recession has ended we'll have the fun and games involved in reducing the Federal deficit and paying off all that nice debt we incurred saving the banks.

scangst: some looked a scangst at Nate Silver's use of the second derivative

FYI. That post on the recession-induced problems ...

2009-05-09T11:30:00.000-04:00

FYI.

That post on the recession-induced problems of the rich originated here.

Our correspondent in Memphis has previously posted comments consisting entirely of an essay having to do with economics that originated elsewhere (without attribution or link) using other IDs and names.

Let's get away from math taxonomy debate - it's ha...

2009-05-09T10:43:00.000-04:00

Let's get away from math taxonomy debate - it's hard to see a public debate about second derivatives as a sign of cultural decline. (I think the correct term is a second difference function, from discrete math, but really who cares?)

A bigger issue for this post is that employment figures are noisy. If the weather's nice in January, fewer people are hired to remove snow, or more substantively, as noted in one of the posts above, 9-11 caused firms to cut jobs.

Differencing magnifies the size of these shocks relative to the signal provided, which may account for some of the "false starts" that appear in the data. One way to deal with this is to take a three-month moving average of the final series, since the shocks then tend to average out. I think this series would be more helpful in diagnosing inflection points.

Lewis

While it's true that much of current US employment...

2009-05-09T10:18:00.000-04:00

While it's true that much of current US employment being created consists of government jobs (Census or otherwise), it's been this way for at least a quarter century now, and is nothing new.

When the US began losing manufacturing jobs in earnest, we replaced them with tech jobs, those in the professions, various low-level service jobs (such as waitressing and bartending), and more government jobs. When the US began losing tech jobs as well, we replaced them with more low-level service jobs, and even more government jobs.

So for quite a while now, three areas of the economy have seen consistent job growth (not counting bubbles such as in construction which was powered by housing): the professions, low-paying service jobs, and government jobs. Practically the only goods of physical value where the US is now a net producer are certain natural resources.

This creates a bit of a donut hole. Those well off enough to enter the professions or similar high-end service sector jobs have been doing fine. Those at the bottom end may not have been doing that well, but there have at least been a glut of low entry jobs that have kept unemployment lower than it otherwise would have been. What of those in between? Basically the only growing group of middle class jobs that offer benefits and upward mobility is government jobs, which I, as a moderate liberal, see as potentially dangerous. It's one thing for government to provide a minimal safety net, but government as primary employer is a situation we probably want to avoid.

The problem for right-wingers and neoliberals, of course, is that the only way to curtail government jobs is to bring back the types of jobs where the worker has power and private sector unionization will probably re-establish itself. They'd much rather not, and just keep the US an economy of bartenders and hairdressers. The political problem with this is that this tends to produce a rather miserable, static economy.

The choices are thus (1) to allow back lucrative private sector jobs that will re-create the economic dynamics of the 60's and 70's in a hurry, or (2) continue to hollow out US employment, keep the economy on a tightrope, and let government employment flourish. Whatever they may claim, they probably prefer (2), as they themselves won't be hurt for the most part, and any long term damage can simply be looped back and blamed on the government. What they really want is for workers who'll provide the productivity of a technology-based private sector industry, but with the malleability and bargaining position of most workers in low level service sector jobs today. A fundamentally 19th century dynamic, in other words.

For various reasons (i.e. progress), the 19th century is never coming back. Any futile attempt along these lines will probably end up devastating the US in time for (3) socialist Europe and communist China to win.

How a prolonged recession would affect all this is unclear. On the one hand, strong economic shocks have often been used to force through right-wing economic programs that would otherwise have no chance of passing. On the other, that doesn't seem to be the prevailing mood these days, and American democracy is much shrewder and better developed than the third world countries where that's happened. Much of the economic movement since Reagan has only been possible because the deterioration of average living standards has been gradual and under the surface. Will this recession lay it bare? Possibly, but only if it's sharp enough, which means it's not worth it. The political tide has already turned, anyway.

@Mike in Maryland.

Haha, great work. To Carl/No Brainer/whatever other sock puppet ID's you're cowardly hiding behind: I don't know much about Nate, except that since the election he's become an online superstar and a rising media figure. The only laughingstock here is you, who even before being exposed as a dishonest sockpuppet, pathetically believed that a beloved fellow right wing troll accomplished anything on this forum besides embarrassing himself.

The next time someone claims to have "once been a fan of this site, but..." I'll be sure to check the Blogger ID.

Christ. is that the best you can do? Using quantum...

2009-05-09T07:35:00.000-04:00

Christ. is that the best you can do? Using quantum physics to refute someone's claim that time is continuous in economic theory?

And spelling "Planck" wrong while you're at it... ;

whispers said... "People who know something a...

2009-05-09T06:00:00.000-04:00

whispers said...

"People who know something about math and are being pedantic about the difference between "second derivative" and "second difference" look a bit silly to those of us with even more of an education in math.

Until statistics are continuously updated, and not just at regular intervals, we will not have access to actual second derivatives. And yet time is a continuous phenomenon, so it is more than reasonable to refer to time-dependent variables using the continuous language of differential calculus.

Nate is using difference equation data to make a point about continuous-time variables. Get it?

People who are pedantic and wrong are really tiresome."

I just have to do this.

1. Time isn't continuous, according to physics. A time of length < 10^-42 or so doesn't have any physical meaning (look up Plank time for this), thus time is really discrete. And slightly less pedantically,

2. Employment (or unemployment) is also a discrete quantity, which means a true second derivative would be zero (no change) or infinity (someone just lost/gained a job, or a fraction thereof). BTW, this also means the intermediate theorem can't be used.

But, I would also hope that everyone would understand what Nate was getting at.

People who incorrectly criticize people who are pedantic and wrong are really tiresome. :)

(Now queue someone else to show why what I said wasn't correct either...)

"it's losing jobs less quickly. That is, the secon...

2009-05-09T05:32:00.000-04:00

"it's losing jobs less quickly. That is, the second derivative of the employment rate -- the change in the rate of change -- has improved."

Actually, that means the FIRST derivative has improved (becoming less negative). The information we know about the second derivative given the quoted statement is not that it has improved, but that it has a positive value. It doesn't have to "improve" further, as just holding at its current value will make the unemployment go down eventually.

Can't anybody here spell? No one noticed that the...

2009-05-09T04:25:00.000-04:00

Can't anybody here spell?

No one noticed that the very first word in the title of this post is misspelled?

It's "hurray",Nate,not "horray."

To the other math weenies complaining about the fi...

2009-05-09T03:31:00.000-04:00

To the other math weenies complaining about the finite difference, c'mon give Nate a break. OF COURSE he meant in the limit of the interval shrinking to zero. :)

I once sat through an econ lecture where the prof kept talking about rate of change as the measurement is taken over smaller and smaller intervals. At one point I almost broke and stood up to shout "It's a derivative! For god's sake just say derivative, our heads won't explode!."

Carl/No Brainer [/Smoking Aces/Donald/etc, etc] th...

2009-05-08T23:50:00.000-04:00

Carl/No Brainer [/Smoking Aces/Donald/etc, etc] the sock puppet, that is.

@Mike in Maryland I say, I say that kid is about ...

2009-05-08T23:25:00.000-04:00

@Mike in Maryland

I say, I say that kid is about about as sharp as a pound of wet leather. What a schnook. ;)

Prag, Correction - right click, not left. I can ...

2009-05-08T23:23:00.001-04:00

Prag,

Correction - right click, not left.

I can be somewhat dyslexic at times when it comes to left/right when giving directions!! VBG

Mike in Maryland

My Blogger ID is http://www.blogger.com/profile/02848893412251095965

Mike in Maryland- good catch. I will keep my eye o...

2009-05-08T23:23:00.000-04:00

Mike in Maryland- good catch. I will keep my eye out for blogger ID's that end in 1066.

Pragmatus- thanks for correcting my typo on laughingstock and not pointing it out! :)

Prag, If you haven't found it yet, left click on ...

2009-05-08T23:21:00.000-04:00

Prag,

If you haven't found it yet, left click on your user ID in any of your posts to open the profile in a new tab or new window. Then click on the 'Edit Profile' button and make any and all changes you wish to make.

You CAN change your profile name, but the Blogger ID remains the same.

Mike in Maryland

My Blogger ID is http://www.blogger.com/profile/02848893412251095965

People who know something about math and are being...

2009-05-08T23:11:00.000-04:00

People who know something about math and are being pedantic about the difference between "second derivative" and "second difference" look a bit silly to those of us with even more of an education in math.

Until statistics are continuously updated, and not just at regular intervals, we will not have access to actual second derivatives. And yet time is a continuous phenomenon, so it is more than reasonable to refer to time-dependent variables using the continuous language of differential calculus.

Nate is using difference equation data to make a point about continuous-time variables. Get it?

People who are pedantic and wrong are really tiresome.

All of you people bashing Nate's calculus might wa...

2009-05-08T23:01:00.000-04:00

All of you people bashing Nate's calculus might want to do a little brushing up yourselves.

Divide the difference in the employment numbers by 1 month (the time interval between data points) and you get a change per unit time. Or the average derivative of the employment over that month. Divide the difference in the change column by the 1 month interval and you get the average 2nd derivative.

Of course the numbers are not the exact derivatives at specific points (although by the mean value theorem, they must be the derivative at some point during the month). They are obviously average derivatives for the month-long intervals.

Do I detect a pattern here? The I tried my best t...

2009-05-08T22:59:00.000-04:00

Do I detect a pattern here?

The I tried my best to beat the system but the system put me back in my place They maintained a delicate balance where no one got in nobody's face commenter is in the building.

Jen gets best post o' the day award, for this: "...

2009-05-08T22:34:00.000-04:00

Jen gets best post o' the day award, for this:

"You are right Carl, Nate is such a laughingstock he is on Time's list of 100 Most Influential People. I am sure you are just upset because he assed you out since you were #101."

☺

Mike in Maryland...

I didn't even know there was a profile I could edit. Learn something every day...