Posts filed under “Mathematics”

Is China Really Funding the US Debt?

I keep hearing people erroneously claim that China is funding US deficit spending. It seems that every eejit with a fundamental misunderstanding of mathematics (and access to Xtranormal‘s animated talking bears) has been pushing this concept.

It turns out to be only partially true — and by partially, I mean 7.5% true. But that means the statement is 92.5% false.

The biggest holders of US debt are American individuals, institutions, and Social Security. We own more than 2 out of every 3 dollars of US debt — about over 67%. Hence, we depend far less on the kindness of strangers than you might imagine if your listen to the intertubes.

Those viral animated bears may be clever, but they sure suck at math.

Total United States’ public debt was ~$13.562 trillion at the end of the fiscal year (30 September 2010). As of last week, January 4, 2011, the United States’ total public debt outstanding has surpassed 14 trillion dollars.

Political Calculations has whipped up a chart showing exactly who is holding US debt, and funding our deficit:

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click for bigger graphic

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Sources:
U.S. Treasury Department:
Monthly Statement of the Public Debt of the United States (September 30, 2010)
Major Foreign Holders of Treasury Securities. (At end of September 2010)

Category: Credit, Mathematics, Really, really bad calls

Population 7 Billion

Population 7 Billion” is a 7-part National Geographic series on global population.

With the worldwide population expected to exceed seven billion in 2011, National Geographic magazine offers a 7-part series examining specific challenges and solutions to the issues we face. The magazine introduces the series with its January cover story “7 Billion,” offering a broad overview of demographic trends that got us to today and will impact us all tomorrow. The first in-depth story will appear in the March issue, focusing on humans’ impact on the planet’s geology. Other stories will follow throughout 2011.

See photos from 7 Billion:

Category: Mathematics, Video

Mathematical Doodling

Fantastic mathematical doodling:

Site is here:

http://vihart.com/

Hat tip NY Mag

Category: Mathematics, Video

Estimates of Wealth Distribution Are Widely Wrong

I’ve been meaning to get to this chart for some time, so I am glad Good reminded me to: The actual United States wealth distribution plotted against the estimated and ideal distributions across all respondents. The actual United States wealth distribution plotted against the estimated and ideal distributions of respondents of different income levels, political…Read More

Category: Current Affairs, Mathematics, Psychology

Asymmetrical Motivation & The .299 Hitter

There is a fun mathematical discussion in the NYT Sports section today worth looking at. It turns out that major league hitters on the verge of a 3 handle batting average — .300 — hit an astounding .463 on their last at bat of the season: “Two economists at the Wharton School of the University…Read More

Category: Mathematics, Sports

Thaler on Tax Cuts

University of Chicago Behavioral Economist Richard Thaler drops some hard analysis on the tax-cut-at-any-price crowd in his NYT column this week: “Want to give affluent households a present worth $700 billion over the next decade? In a period of high unemployment and fiscal austerity, this idea may seem laughable. Amazingly, though, it is getting traction…Read More

Category: Mathematics, Taxes and Policy

Conditional Risk (or, trouble when you misapply stats)

XKCD:

Category: Mathematics, Weekend

Who Gets What If Tax Cuts Are Extended

The NYTimes graphic department has your Sunday morning chart porn regarding the extension of tax cuts. Its an illustration fueled by data from the Tax Policy Center, a nonpartisan research organization. The graphic shows how much Americans have gotten so far broken down by income groups. And it calculates that extending all of the Bush…Read More

Category: Mathematics, Politics, Taxes and Policy

Whatever Happened to that Apple iPhone Recall?

“If the current betting trends are to be believed, it now seems certain that a recall is in the cards” -Paddy Power, Irelands Biggest Bookmaker July 14, 2010 press release > Speaking of dumb bets: Its time to revisit a recent prediction market “winner,” and review the strengths and weaknesses of these markets: Recall this…Read More

Category: Mathematics, Really, really bad calls, UnScience

10 Habits of Mind for Investors

This comes from a math blog by a teacher called WITHOUT GEOMETRY, LIFE IS POINTLESS (get it?).

There is a recent post I wanted to reference — Habits of Mind — that was originally written for math students. With a few small changes, it can be readily adapted to thinking about markets, risk, investing, etc.

Have a go at it:

Habits of mind

1. Pattern Sniff
. . .A. On the lookout for patterns
. . .B. On the lookout for shortcuts

2. Experiment, Guess and Conjecture
. . .A. Can begin to work on a problem independently
. . .B. Estimates
. . .C. Conjectures
. . .D. Healthy skepticism of experimental results
. . .E. Determines lower and upper bounds
. . .F. Looks at small or large cases to find and test conjectures
. . .G. Is thoughtful and purposeful about which case(s) to explore
. . .H. Keeps all but one variable fixed
. . .I. Varies parameters in regular and useful ways
. . .J. Works backwards (guesses at a solution and see if it makes sense)

3. Organize and Simplify
. . .A. Records results in a useful way
. . .B. Process, solutions and answers are detailed and easy to follow
. . .C. Looks at information about the problem or solution in different ways
. . .D. Determine whether the problem can be broken up into simpler pieces
. . .E. Considers the form of data (deciding when, e.g., 1+2 is more helpful than 3)
. . .F. Uses parity and other methods to simplify and classify cases

4. Describe
. . .A. Verbal/visual articulation of thoughts, results, conjectures, arguments, etc.
. . .B. Written articulation of arguments, process, proofs, questions, opinions, etc.
. . .C. Can explain both how and why
. . .D. Creates precise problems
. . .E. Invents notation and language when helpful
. . .F. Ensures that this invented notation and language is precise

Read More

Category: Apprenticed Investor, Investing, Mathematics, Psychology, Rules