All Spanish youth have cell phones

Todos los jóvenes españoles tienen móvil -- that is, all Spanish youth have cell phones. From tuexperto.com, via Microsiervos, both in Spanish.

As the authors of Microsiervos point out, this is almost certainly not true. Rather, some Spanish youth have no cell phone, and some have two or more. The average Spanish youth may have one cell phone, but the number of cell phones one has is not an indicator random variable. (That is, it doesn't take the value 0 if you have no cell phone and 1 if you have a cell phone.)

(And although the pictures show babies, "youth" here are people from 15 to 35.)

Degree Clinical Protection

A commercial for "Degree Clinical Protection" deodorant said: "Do you know one in four people think they sweat more than normal?"

So another one in four people are in denial, since the number of people who sweat more than normal is probably about half. (I'm assuming that "sweating more than normal" is the sort of thing one would deny, which seems reasonable, at least in the perspective of a deodorant commercial.)

I'm reminded of the often-quoted fact that three-quarters of all incoming students at [insert prestigious university here] think they're going to be in the top quarter of their incoming fact.

(The amazon.com page has a description beginning "Did you know one in four Americans worry about excessive sweating?", which I don't have a problem with, because the word "excessive" doesn't have the same statistical connotations.)

Beauty is in the eye of the beholder

Ben Goldacre, writing in Bad Science, tells us the story of how he was contacted by a PR firm which wanted him to concoct some equations that would "prove" that certain celebrities had sexier walks than certain other celebrities, as part of a promotion for Veet hair removal cream. I am not making this up. It's an extended version of his column in the Guardian.

The press release seems to have beeen reproduced by about a zillion British newspapers, usually in a shortened version; the longest version I could find is here, and I'll be quoting from it.

JESSICA Alba, the film actress, has the ultimate sexy strut, according to a team of UK mathematicians. Beauty is no longer in the eye of the beholder - it can now be worked out using a simple mathematical formula.

Bullshit! And this isn't just me being bitter that I might not fit some social standard of beauty. It's me being bitter that mathematics is being "used" in this way. In Goldacre's column, we learn that there was no team. Richard Weber at Cambridge is the mathematician who's mentioned there, but only after Goldacre was contacted -- and Goldacre as far as I can tell is a medical doctor. (By "there" I mean Goldacre's blog post; I can't find a version of the press release that mentions Weber.)

The academics found that it is the ratio between hips and waist that puts the sway into a woman's walk - and the nearer that ratio is to 0.7, the better.

No they didn't! This seems like the stuff you see out there every so often about the Golden Ratio making things more beautiful -- and in fact that ratio's been used to sell pants! -- where there's some "magic number". There's at least some justification for the 0.7 number, though, in that Real Scientists have done studies, although the preferred ratio varies by culture. And it never seems to be given to more than one decimal place, which suggests that a few inches don't matter. Apparently Weber made a more nuanced comment that got cut down to this.

This ratio provides the body with the right torso strength to produce a more angular swing and bounce to the hips during the walking motion.

Furthermore, the waist-to-hip ratio might actually be important for physical attractiveness, but nobody said that had anything to do with the walk. I don't know much about biomechanics, though. But it looks like the causality just isn't there.

Oh, and they screwed the survey up so badly that it doesn't even mention anything that hair removal cream could actually do. You'd expect a study by a hair removal cream company to say that having smooth, shiny, hairless [insert body part here] was an important part of beauty.

Fortunately, they're just using this to sell hair removal cream. Recent studies have also shown that studies which are funded by pharmaceutical companies are far more likely to say that drugs do something goodthan studies which are not funded by pharmaceutical companies; that sort of hijacking of the scientific apparatus is a lot more insidious, as people could actually die.

I'm not saying that beauty can't be encapsulated in some sort of formula. But it'll be a lot more complicated than this one. (In fact, it might not be a "formula" at all, in the sense that you put in numbers which describe the person and get out a numerical rating of their beauty; much more feasible would be a recommendation system like that on Netflix or Amazon. As I understand it, those systems work by recommending books or movies to you that people who have bought the same books or rented the same movies as you also liked.)

And I'm skeptical of any formula that says that the same people will seem beautiful to everyone, because that's simply not true. I think someone could come up for a formula that will tell them who I am likely to find beautiful -- there are definitely patterns. But my tastes are not the same as yours. And don't try to tell me they should be.

P. S. I moved into my apartment a year ago today. As I sit here, I look out my kitchen window and see a truck from the movers I used. This is probably not a coincidence, though, as September 1 is kind of a big moving day in my neighborhood.

how many Asians are there in Philadelphia?

In today's Philadelphia Inquirer: Asian market interests banks, about how there are banks in Asian-American enclaves of Philadelphia (such as Chinatown) that specifically target that market. There are two major reasons why this market has been poorly served by traditional banks, according to the article: the language barrier, and the fact that many Asian-Americans don't have as much credit history or financial documentation as other people in similar financial situations, because they tend to deal more in cash.

The online version of the article doesn't include the following chart of ten-county population by race, attributed to the American Community Survey of the U. S. Census Bureau, which caught my interest:

	2002	2005	Percentage change
White	3928263	4036597	2.76%
Black or African American	1115683	1167451	4.64%
American Indian and Alaska Native	8817	8848	0.35%
Asian	209246	250552	19.74%
Native Hawaiian and Other Pacific Islander	1262	1768	40.10%
Hispanic or Latino	319101	371502	16.42%
Total population	5667690	5747353	1.41%

The point of the table, of course, is to illustrate that the Asian market has been growing in this area faster than the population as a whole, and that therefore it is logical that banks would be reaching out to this community.

Now, when I read this, something seemed suspicious. The population in every category except the neglible "American Indian and Alaska Native" one went up by at least 2.76%. But the total population went up by only 1.41%. Something is wrong here.

If you then add up the first six entries in each column, you get 5,582,372 and 5,836,718, respectively. For some strange reason, the sum of the racial numbers is 85,318 less than the total population in 2002, but 89,365 more than the total population in 2005. The obvious explanations are the following:

• "Hispanic or Latino" is being treated differently than the other items here, which is actually fairly common in discussions of race in America; basically if your ancestors come from somewhere Spanish-speaking, then you're somehow outside of the usual "race" categories.


• A lot more people have suddenly started to identify as multiracial between 2002 and 2005. A lot. Three percent of the total population. I'm aware that a lot more people have started to identify as multiracial recently instead of feeling like they have to pick one identity or the other, but it doesn't seem like it could happen that fast.

Usually on tables like this, one sees some note saying that the various pieces of population don't add up to the total population, due to certain minor categories not being listed, or due to people being included in more than one category. But there is no such note.

I had actually been anticipating something like Simpson's paradox, but it doesn't seem to be anything that complicated.

By the way, the ten-county area here is Bucks, Delaware, Chester, Montgomery, and Philadelphia counties in Pennsylvania; Camden, Burlington, Gloucester, and Atlantic counties in New Jersey; and New Castle county in Delaware. This strikes me as being slightly "off"; I would replace Atlantic with either Mercer or Salem. I suspect this doesn't make a huge difference in the data; however, it might be an example of "selective reporting", where one draws the boundaries in a nonstandard way to make some sort of point. The census bureau itself uses a nine-county area (the first eight above, plus Salem County, New Jersey); I'd say the most common definition of the Philadelphia area is as the first eight counties above.

more on that crazy Laffer curve

A few days ago I posted about some particularly egregious curve-fitting in the Wall Street Journal, in which corporate tax rates versus tax revenue in different countries was plotted, and a curve was fit to the data to make it look like we were on the right side of the Laffer curve. (Incidentally, people on the right economically believe we are on the right side of the Laffer curve, and therefore taxes should be cut; people on the left economically believe we are on the left side of the Laffer curve and therefore taxes should be raised.)

Someone else called this Best Curve-Fitting Ever (sarcastically, of course, if you take a look at the actual pictures); the comments are rather interesting, and do a better job of explaining the economic issues underlying this than I could.

it's just a phone!

One-in-three Americans want iPhone -- or so Macworld claims. (Yeah, they're not biased at all.)

It's very thinly veiled advertising; in two clicks from that article I found the original press release from the research company. The "article" says:

Lightspeed Research surveyed 39,000 people on its US online panel in the days following the launch of the device on 29 June - and the research findings are staggering.

I'm not sure if I trust this "online panel". For one thing, as a friend of mine pointed out, people who are online are more likely to want an iPhone. Second, the "article" goes on to say:

Thirty-two per cent of those surveyed who do not currently own an iPhone stated that they do intend to purchase one, with 8 per cent planning to purchase in the next three months and 22 per cent planning to purchase "some time in the future", the researchers said.

First of all, 8 plus 22 isn't 32, and even with rounding error that doesn't work out. More importantly, though, there are plenty of things that I've said I was going to buy in the future that I never ended up buying; if I put off buying something for long enough then I realize that I don't want it after all.

My friends seem like the sort of people that would want iPhones, and I think that not even one-third of them would want an iPhone -- although now I'll ask around.

Furthermore, you don't need to ask 39,000 people to get these sorts of results. But it sounds more impressive if you do. Most polls for, say, political campaigns have a sample size of about 1,000 and a 3% margin of error. With a well-chosen sample of 39,000 you should get a margin of error of about 0.5% (the margin of error scales as the inverse square root of the sample size), but I doubt this sample is well-chosen. I suspect that Lightspeed Research (the polling company) wasted their time asking this many people, because their sample is no good. They claim it is at their FAQ, and I believe their claim that the demographics of the panel are the same as the general population. However, they say that "A panel is comprised of people who have opted-in to share their views on products and services and recruited solely for market research purposes." The sort of people who are likely to be in such a panel are people who spend too much time online -- exactly the iPhone's target market!

The moral of this story: just because you asked a lot of people doesn't make you right.

If you're going to lie with numbers, at least be subtle about it

Mark C. Chu-Carroll at Good Math, Bad Math comments on A Laughable Laffer Curve from the WSJ.

In economics there is the Laffer curve, which posits that increasing tax rates increases government revenue up to a certain tax rate, after which increasing taxes actually decreases revenue because it discourages people from producing wealth. A lot of macroeconomics is devoted to determining what the Laffer curve looks like, in order to argue that taxes should be raised/lowered. Chu-Carroll explains it better than I can; you should read his post.

The Wall Street Journal is far to the right economically, and shows this by drawing a "curve" fit to a bunch of points that is clearly contrived to make it look like lowering corporate taxes in the US is a Good Idea. I know that I don't know enough economics to comment. But I do know that the WSJ could have been a little more subtle.