statistics
bioephemera | March 17, 2009I know I've typed out some howlers in my day, so I say this with all due humility. But this post over at iO9 had me rolling on the floor last night:
Paul Murtaugh, a statistician at Corvallis' Oregon State University, claims that our carbon legacy isn't just limited to our own emissions, but 50% of our children's (The other parent gets the other 50%). And 25% of their children's, and so on, and so on. He arrived at this estimate using math: Murtaugh used UN population projections, which say that after 2050, birth rates in all countries will be 1.85 children per woman, on average. Then he took…
mikethemadbiologist | March 12, 2009....AARRGGHH!!! One of my pet peeves are political polls that don't get at how self-described political identification matches actual opinions: in other words, are some moderates actually like liberals or conservatives and so forth. By way of Matt Yglesias, we find that the Center for American Progress recently polled people in the U.S. by asking them 39 questions about political issues. The respondents were asked to disagree or agree on a scale of 0 - 11.
The study (pdf) is actually pretty thorough. They describe, in tables, how various self-described groups answered classes of…
revere | March 3, 2009The United States has an influenza surveillance system composed of five overlapping parts. You can get an overview of each here. In 2004 laboratory confirmed deaths from influenza in children (persons less than 18 years old) was made a notifiable cause of death by the states and through this we have been able to get a statistical snapshot of this most tragic kind of influenza mortality. There were 8 such deaths in four states reported this past week, occurring from February 1 to February 18, making the total for this flu season 17. Bacterial co-infection with Staph was seen in 10 of the 17…
mikethemadbiologist | January 6, 2009Gallup has released a poll that shows that the percentage of Americans who use the internet for more than an hour has increased to 48 percent. But some of the claims of change in use by demographic group puzzle me--I don't think they're significant.
First, the data (percent who use the internet for more than an hour per day):
(click here to embiggen)
Some of the changes don't really make sense to me. Does anyone really think that the number of 'heavy' userpost-graduates (Ph.Ds, masters, laywers, M.Ds) increased by twelve percent over the last year? Or that unmarried users increased by ten…
edyong | December 23, 2008Three years ago, Lawrence Summers, former president of Harvard University, claimed that genetic differences between the sexes led to a "different availability of aptitude at the high end". His widely derided led to his dismissal, but is views are by no means uncommon. In the same year, Paul Irwing and Richard Lynn conducted a review of existing studies on sex differences in intelligence and concluded:
"Different proportions of men and women with high IQs... may go some way to explaining the greater numbers of men achieving distinctions of various kinds for which a high IQ is required, such…
goodmath | December 13, 2008
I recently got an offer from someone at No-Starch Press to review the
newly translated book, The Manga Guide to Statistics. I recieved the book a couple of weeks ago, but haven't had time to sit down and read it until now.
If you haven't heard of the "Manga Guides", they're an interesting idea. In Japan, comic books ("Manga") are much more common and socially accepte than they typically are in the US. It's not at all unusual to see Japanese adults sitting in the subway reading Manga. Manga has a very distinctive artistic style, with its own
set of common artistic conventions. The Manga…
mikethemadbiologist | November 18, 2008Many in the Punditocracy are proclaiming that the U.S. is a center-right country. While it's pretty obvious that they're saying this to justify their feeble pronouncements, that's not what really bugs me about this center-right hooey.
That statement is based on the observation that the majority of voters describe themselves as either moderate or conservative. But this is a stupid way of looking at this result because it presumes that the terms liberal, moderate, and conservative have accepted, standard meanings. That presumption should be called into doubt in any country where a…
goodmath | October 28, 2008 Before I get to the meat of the post, I want to remind you that our
DonorsChoose drive is ending in just a couple of days! A small number of readers have made extremely generous contributions, which
is very gratifying. (One person has even taken me up on my offer
of letting donors choose topics.) But the number of contributions has been very small. Please, follow the link in my sidebar, go to DonorsChoose, and make a donation. Even a few dollars can make a
big difference. And remember - if you donate one hundred dollars or more, email me a math topic that you'd like me to write about, and I'…
mikethemadbiologist | October 15, 2008I've written about journal impact factors before, largely to argue that there are better statistics than the traditional impact factor. But an excellent editorial in the Oct. 10 issue of Science by Kai Simons points out a very obvious problem with how impact factors are used (italics mine):
Research papers from all over the world are published in thousands of Science journals every year. The quality of these papers clearly has to be evaluated, not only to determine their accuracy and contribution to fields of research, but also to help make informed decisions about rewarding scientists with…
rallain | September 28, 2008When mowing the lawn, I like to listen to podcasts. One of my favorites is [Buzz Out Loud](http://bol.cnet.com). This weekend, I was listening to episode 817 and one of the topics of discussion was MySpace and their DRM free music stuff. [Wired](http://blog.wired.com/music/2008/09/myspace-launche.html) had a description of what they were going to do. That is not my point. The point is the claim that you could make an infinite number of playlists. How about I calculate (or estimate) the number of different playlists one could make.
First, the idea behind the idea. Calculating the number…
revere | September 11, 2008I heard it again the other night. One of the TV chin strokers talking about this poll or that poll showing Obama (or McCain) ahead with a "statistically insignificant" lead, and I thought to myself, no one who knew much about statistics would use a phrase like that. Strictly speaking, while there may be something like statistical significance, there is no statistical insignificance. It is a nonsensical term that is becoming part of the language by use, so I know I can't stop it with a blog post. If I could, I would, because it invites serious misunderstanding in the speaker and listener alike…
mikethemadbiologist | August 12, 2008As Jesse at Pandagon notes, even though the presidential race is stagnant in that the numbers aren't shifting much, that's not the same as the race being in a dead heat. This would be obvious, if your typical political reporter wasn't a mathematically illiterate moron.
Yes, I know that there's only one poll that matters and it's in November, blah, blah, blah. But based on the available poll data, there's no way this is a dead heat. Why? Because, in 40 out of 41 polls since Clinton dropped out of the race, Obama has led McCain. If they truly were in a dead heat (i.e., 50/50), the…
mikethemadbiologist | July 28, 2008Who woulda thunk it? A recent paper in PLoS One argues that the NIH review process uses far too few reviewers to claim the level of scoring precision that the NIH provides.
NIH grants are scored on a scale from 1.0 to 5.0, with 1.0 being the best; reviewers can grade in tenths of a point (i.e., 1.1, 2.3, etc.). The authors, using some very straightforward statistics, demonstrate that four reviewers could accurately assign whole integer scores (1, 2, 3...), but to obtain reliable scores with a precision of 0.01, a proposal would require 38,416 reviewers.
Not going to happen. Keep in mind…
mikethemadbiologist | July 19, 2008A recent poll breaks down the support for McCain and Obama among Jews by denomination:
I can't figure out why there is such a sharp difference. It's not like abortion would be a wedge issue (an aside: Orthodox Jews comprise 7-12% of the population; in this poll, they were 8% of the sample). Age can't be an issue either: Conservative Jews trend slightly older, and Orthodox slightly younger. It would be interesting to see how denomination is correlated with religious denomination and with importance of Israel's security.
Unfortunately, like every other poll where they claim to release the…
evolgen | June 23, 2008Dak at Fire Joe Morgan asks:
I've been watching a fair amount of SportsCenter / BBTN today, and every two minutes someone mentions that there are "seven teams going for a sweep in an interleague series!", as if this is some sort of big deal. There are fourteen interleague series this weekend. If every match were a coin-flip, wouldn't we expect exactly seven teams to be going for sweeps in the third game of a series?
We'll start by assuming each team has an equal probability of winning each game, and the results of each game are independent. After one game, you're guaranteed that one team…
evolgen | May 22, 2008
On Tuesday night, the National Basketball Association (NBA) held their annual draft lottery. In the draft, each team is given the opportunity to select a few players that have declared themselves eligible for the draft (either after completing at least one year of college in the United States or being from another country and over 18 years old). The order of picks in the NBA draft is determined with a goal of awarding earlier picks to teams that performed the worst the previous season. However, rather simply giving the worst team the first pick, second worst the second, etc., the NBA takes…
mikethemadbiologist | May 16, 2008I was reading this post about the possible strengths and weaknesses of Clinton and Obama among different demographic groups, and I grew very annoyed.
Not at Digby, but the whole debate. What's really frustrating about most voting demographic stories (besides the obvious, which is that they don't have much to do with actual governing) is that I have no way to evaluate the claims made. Sometimes there are bar graphs that show how one group compares to another (blacks vs. whites, old vs. young, etc.). On very rare occasion, there is a two-by-two table, but that's still not enough. If news…
goodmath | April 14, 2008 I'd like to start with a quick apology. Sorry that both the abstract algebra and the new game theory posts have been moving so slowly. I've been a bit overwhelmed lately with things that need doing right away, and
by the time I'm done with all that, I'm too tired to write anything that
requires a lot of care. I've known the probability theory stuff for so long,
and the parts I'm writing about so far are so simple that it really doesn't take nearly as much effort.
With that out of the way, today, I'm going to write about probability distributions.
Take a probabilistic event. That's an event…
goodmath | April 9, 2008 The first key concept in probability is called a random variable.
Random variables are a key concept - but since they're a key concept of the
frequentist school, they are alas, one of the things that bring out more of
the Bayesian wars. But the idea of the random variable, and its key position
in understanding probability and statistics predates the divide between
frequentist and Bayesian though. So please, folks, be a little bit patient,
and don't bring the Bayesian flamewars into this post, OK? If you want to
rant about how stupid frequentist explanations are, please keep it in the…
goodmath | April 7, 2008 To understand a lot of statistical ideas, you need to know about
probability. The two fields are inextricably entwined: sampled statistics
works because of probabilistic properties of populations.
I approach writing about probability with no small amount of trepidation.
For some reason that I've never quite understood, discussions of probability
theory bring out an intensity of emotion that is more extreme than anything else
I've seen in mathematics. It's an almost religious topic, like programming
languages in CS. This post is intended really as a flame attractor: that is, I'd request…