Hooray: The Second Derivative of the Unemployment Rate Improved

http://www.fivethirtyeight.com/2009/05/horray-second-derivative-of.html

by soundsop • 17 years ago

38 16 17 years ago

mustpax2• 17 years ago

Using the term second derivative obscures the meaning here somewhat. 'Deceleration' would be a more accessible concept to use to describe what's happening. It doesn't mean we're going backwards yet (i.e. net employment gains), but the rate of loss is slowing. At least that's what they told me in Physics class.

mattyb• 17 years ago

I don't think there's any obscurity; this is high school calculus. If the rate of change (first derivative, negative in this case) is slowing, that means the second derivative is positive here. I'm not yet convinced this is a sign of things to come, however; there are five inflection points in his table where the rate of loss improves.

mustpax2• 17 years ago

I'm not saying the terminology is wrong or anything like that. I'm just saying 'deceleration' is a more concise and comprehensible way of talking about changes in the second derivative. You might be surprised how little high school calculus most people have retained.

smanek• 17 years ago

I think 'deceleration' is more ambiguous.

I tend to think of derivatives taken with respect to time in terms of high school physics.

Let x = postion

x' = velocity

x'' = acceleration

x''' = jerk

(and, incidentally, the 4th through 6th derivatives of position are known, respectively, as 'snap', 'crackle', and 'pop' ;-))

utx00• 17 years ago

you sir, is a genious.

jmtulloss• 17 years ago

It might be kind of obscure, but it emphasizes how far we'll go to find good information in a bad enconomy. It's like when people ask you if you know somebody at a party and say "sure, the place belongs to my girlfriend's 2nd best friend's 3rd cousin twice removed" Nobody knows what a 3rd cousin twice removed is, but they know its a long way from being relevant.

Not that this isn't relevant, but it's not an improvement in employment percentage, which is what people who don't need to speculate about the economy really care about.

biohacker42• 17 years ago

I never thought I would be a fan of writing about statistics. But Nate Silver has become a must-read.

joe_the_user• 17 years ago

Uh,

Sure, it sounds clever but taking the second derivative of noisy data is poor statistics as far I'm concerned.

benmathes• 17 years ago

Keep in mind that unemployment figures are not a simple polynomial. Specifically, an _improvement_ in the second derivative (not even necessarily positive) doesn't directly imply that we're going to improve. The article mentions this too:

>----------------------------------------------------

The $787 billion question, of course, is whether a decrease in the rate of job losses indeed portends a recovery, or whether such data is subject to false starts.

>----------------------------------------------------

I'm all for optimism, but there's enough short-term fluctuation in economic statistics that this is like getting the faintest whiff of baked goods and wondering whether we're all getting donuts next week.

kqr2• 17 years ago

You can also quote an article by using asterisks:

From the help http://news.ycombinator.com/formatdoc :

Text surrounded by asterisks is italicized, if the character after the first asterisk isn't whitespace.

patrickg-zill• 17 years ago

Contrarian view: http://www.shadowstats.com/alternate_data

"actual" unemployment if computed the way it was in 1992: 19% for "shadowstats version of U6" versus "official U6"

UncleOxidant• 17 years ago

Also note that the "birth-death" model fudge-factor they used for April was 226,000 which was about double what it was for March.

Watch out for revisions as well: "February was revised down from -651k to -681k (-30,000) and March was revised from -663k to -699k (-36,000). See a pattern there? That's 66,000 jobs that were reported as existing but revised out later."

http://market-ticker.org/archives/1026-Unemployment-Fried-Da...

gills• 17 years ago

Don't forget the phantom ('seasonal') 60,000 jobs created by temporary hiring for the census...

ojbyrne• 17 years ago

Just a slightly associated random data point. Across the 10 yard border Canada announced their own surprise - 35k net job increase in April: http://www.thestar.com/business/article/631083

Hooray: The Second Derivative of the Unemployment Rate Improved

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