## Monthly Archive for October, 2012

### Sandy and the Ants

I was asked in another thread to refute the notion that Hurricane Sandy is “good for the economy” because at least it will create a lot of construction jobs.

I — and so many others — have so thoroughly debunked this notion in so many venues over the years that I fear I can find nothing new to say, so I’ll leave you with this:

If you find yourself in an argument about this, ask your opponent whether it’s “good for the ants” when you put a stick down their anthill, wiggle it around and destroy their infrastructure. Go ahead and acknowledge that this can sure put a lot of ants to work.

Or, for that matter….

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### Mortgage Solution

The solution to yesterday’s mortgage puzzle:

Commenters pointed to several reasons why biweekly payments of (say) \$500 will pay your mortgage off so much faster than monthly payments of \$1000, but of these by far the most important is that biweekly payments of \$500 add up to 500 x 26 = 13,000 dollars, whereas monthly payments of \$1000 add up to 1000 x 12 = 12,000 dollars. With the biweekly payments, you make the equivalent of 13 monthly payments every year.

In other words, the key observation is that two weeks is not half a month.

My colleague Michael Wolkoff posed this puzzle to me many years ago, and I’m embarrassed to admit I failed to solve it before Michael gave me the solution. I was reminded of it yesterday when I got a biweekly-plan offer in the mail.

### Mortgage Puzzle

I have recently acquired a 30 year mortgage.

Today I’ve received a letter offering to let me make payments on a biweekly basis instead of a monthly basis. If I accept this offer, I will make a biweekly payment equally to exactly half my current monthly payment — and my mortgage will paid off in 23.6 years instead of 30.

Question: How can such a small change in the timing of my payments shave a full 6.4 years off the life of my mortgage?

### The Mourdock Platform

Richard Mourdock, Indiana Senate candidate, has announced his opposition to interference with God’s revealed intent. I presume, then, that he’ll be taking a principled stand against firefighting, medical intervention, federal debt reduction, and unseating incumbent Presidents.

Update: Mourdock now clarifies his position by saying that “God does not want rape”. I’d thought he was saying that if a pregnancy occurs, God must have wanted it, which would seem to be an instance of the general principle that if anything occurs, God must have wanted it. Now we’re told that there is no such general principle — from which I am left to conclude that the only way to tell what God wants is to ask Richard Mourdock. This is a logically consistent criterion, but what if, for example, Mourdock happens to be indisposed at the moment when, say, terrorists attack the White House? How will we know whether it’s okay to resist?

### Debate Number Three

Limited commentary this time, partly because I am no expert on foreign policy so there’s no reason you should care about most of my opinions. On the other hand, the candidates had an exceptionally broad definition of foreign policy, which included trade, deficits, unemployment, education, etc. Commentary also limited by the fact that my attention wandered from time to time.

That said, here are my comments, typed in real time, unedited, not carefully thought through, perhaps in some cases ill-advised:

### Second Debate

My wife, who really ought to have her own blog, heard only the few minutes dealing with immigration and then China and summed up the candidates’ shared position as “We sure love immigrants, but we sure hate foreigners”.

I, by contrast, slogged through the entire thing. Here are my own less brilliant comments, typed in real time while watching the debate; not edited and perhaps in some cases not sufficiently thought through:

### Kidney Failure

So Alvin Roth wins the Nobel Prize for, among other things, figuring out the best way to allocate kidneys subject to the constraint that you’re too damned dumb to use the price system.

Next up: A Nobel prize in medicine for figuring out the best way to prolong your life while repeatedly shooting yourself in the head.

### Krugman — So Right and So Wrong

Paul Krugman offers a nice thought experiment to illustrate why government debt, in and of itself, does not make the country as a whole any poorer:

Suppose that … President Santorum passes a constitutional amendment requiring that from now on, each American whose name begins with the letters A through K will receive \$5,000 a year from the federal government, with the money to be raised through extra taxes. Does this make America as a whole poorer?

The obvious answer is not, at least not in any direct sense. We’re just making a transfer from one group (the L through Zs) to another; total income isn’t changed. Now, you could argue that there are indirect costs because raising taxes distorts incentives. But that’s a very different story.

OK, you can see what’s coming: a debt inherited from the past is, in effect, simply a rule requiring that one group of people — the people who didn’t inherit bonds from their parents — make a transfer to another group, the people who did. It has distributional effects, but it does not in any direct sense make the country poorer.

### So That’s Why It’s Called Graphic Design

A few years back, the British Office of Government Commerce wanted a new logo for etching on (among other things) mousepads and pens, and paid a graphic design firm over \$20,000 to come up with this:

Apparently it never occurred to anyone that mousepads and pens are frequently turned on their sides.

Et voila:

### The Great Debate

Okay, I watched the debate —- and jotted down responses as I watched. These jottings were made in real time while trying to listen to the candidates, and are, I’m sure, in many cases, not as well thought out as they ought to be. But here they are, unedited:

### Wednesday Solution

Monday’s puzzle was open to various interpretations, but under what seems to me to be the most straightforward interpretation, if the number of runners you pass is the same as the number who pass you, you’re the mean runner, not the median.

You can find plenty of correct analysis in Monday’s comment section (see in particular Harold’s perfect comment #39), but here’s a more longwinded explanation:

First, suppose you randomly sample a large number of other runners and discover that half of them are faster than you and half are slower. Then you’re entitled to conclude that you’re the median runner (or, if we’re being careful, you’re entitled to conclude that you’re probably close to the median, since there’s always a chance your sample was unrepresentative).

Now in the problem as given it’s certainly true that half the runners you encounter are faster than you and half are slower. So you might be tempted to use the above reasoning and conclude that you’re the median runner. But that won’t work, because the runners you encounter are not a random sample.

So let’s start over. We might as well assume that you’re the center of the universe, so you’re completely motionless. Everyone who’s faster than you is running forward and everyone who’s slower than you is running backward. People “pass” you when they run past you in the forward direction, and you “pass” them when they run past you in the backward direction.

### Monday Puzzle

It’s a lovely morning, and you are jogging along the lakeshore, along with many others (all in the same direction). Albert is the median runner (that is, he runs at the median speed). Betty is the average runner (she runs at the average — i.e. the mean — speed.)

You notice that the number of runners you pass is exactly equal to the number of runners who pass you.

Can you determine whether you’re running faster or slower than Albert? What about Betty?

Edited to add: When I said you were running “along the lakeshore”, I was envisioning the shore of Lake Michigan; i.e. I meant to say that you’re running, effectively, in a straight line, not a circle. Obviously I should have made this clearer. But it’s a good puzzle either way!