Archive for February, 2009

Failed satellite launch

Wednesday, February 25th, 2009

I asked my brother Andy what the consequences for climate science would be from the failed launch of the Orbiting Carbon Observatory satellite this week.  He pointed me to this, which has a lot of good information, both on this satellite and on the difficulty of doing science with space-based instruments in general.

For those who don’t know about it, RealClimate.org is full of great stuff.

Planck preparing for launch

Sunday, February 22nd, 2009

The Planck Surveyor, the European Space Agency’s satellite-borne microwave background telescope, is preparing for launch on April 16.  Andrew Jaffe has some pictures of the preparations.

Planck will map the microwave background with finer resolution than NASA’s WMAP satellite.  It’ll also cover a considerably broader range of frequencies.  This is helpful in separating the microwave background from other, more local sources of radiation.

I think I’m still officially a member of the Planck team in some sense, although I haven’t done any real work on it.

Does peer review work?

Tuesday, February 17th, 2009

Recently, I’ve been spending a lot of time with the peer review process.  I’ve been revising a couple of papers in response to comments from the referees, and at roughly the same time I’ve been acting as referee for a couple of articles.

Some journals send each article just to a single referee, while others use multiple referees per article.  In the latter case the author and the editor can get some idea of how well the process works by how consistent the different referee reports are with each other.  In particular, if one referee says that a paper has a fundamental flaw that absolutely must be fixed, while the other notices nothing wrong, it’s natural to wonder what’s going on.

In fact, by keeping track of how often this sort of thing occurs, you can estimate how good referees are at spotting problems and hence how well the peer review process works. Let’s consider just  problems that are so severe as to prevent acceptance of the paper (ignoring minor corrections and suggestions, which are often a big part of referees’ reports).  Suppose that the typical referee has a probability p of finding each such problem.  If the journal sends the paper to two referees, then the following things might happen:

  • Both referees miss the problem.  This happens with probability (1-p)2.
  • One referee finds the problem and the other misses it.  The probability for this is 2p(1-p).
  • Both referees find the problem.  The probability here is p2.

A journal editor, or an author who’s written a bunch of papers, can easily estimate the ratio of the last two options: when one referee finds a problem, how often does the other referee find the same problem?  From that ratio you can solve for p and know how well the referees are doing.

In my experience, I’d say that it’s at least as common for just one referee to find a problem as it is for both referees to find it. That means that the typical referee has at best a 2/3 chance of finding any given problem.  And that means that the probability of both referees missing a problem (if there is one) is at least (1/3)2, or 1/9.  I’ll leave it up to you to decide whether you think that’s a good or bad success rate.

The main thing that made me think of this is that in one referee report I sent off recently, I pointed to what I think is a major, must-fix error, and I’m willing to bet the other referee won’t mention it.  That’s not because the other referee is a slacker — I don’t know who it is, or even whether this particular journal uses multiple referees.  It’s because the paper happens to have a problem in an area that I’m unusually picky about. It’s bad luck for the authors that they drew me as a referee for this paper.  (But, assuming that I’m right to be picky about this issue — which naturally I think I am — it’s good for the community as a whole.)

This sort of calculation shows up in other places, by the way.  I first heard of something like this when my friend Max Tegmark was finishing his Ph.D. dissertation.  He got two of us to read the same chapter and find typos.  By counting the number of typos we each found, and the number that both of us found, he worked out how many undiscovered typos there must be.  I don’t remember the number, but it wasn’t small.  On a less trivial level, I think that wildlife biologists use essentially this technique to assess how efficient their population counting methods are: If you know how many bears you found, and how many times you found the same bear twice, you can work out how many total bears there are.

More on the colliding satellites

Sunday, February 15th, 2009

The National Weather Service says

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE JACKSON KY
1145 PM EST FRI FEB 13 2009

...POSSIBLE SATELLITE DEBRIS FALLING ACROSS THE REGION...

THE NATIONAL WEATHER SERVICE IN JACKSON HAS RECEIVED CALLS THIS
EVENING FROM THE PUBLIC CONCERNING POSSIBLE EXPLOSIONS AND...OR
EARTHQUAKES ACROSS THE AREA. THE FEDERAL AVIATION ADMINISTRATION HAS
REPORTED TO LOCAL LAW ENFORCEMENT THAT THESE EVENTS ARE BEING CAUSED
BY FALLING SATELLITE DEBRIS. THESE PIECES OF DEBRIS HAVE BEEN CAUSING
SONIC BOOMS...RESULTING IN THE VIBRATIONS BEING FELT BY SOME
RESIDENTS...AS WELL AS FLASHES OF LIGHT ACROSS THE SKY. THE CLOUD OF
DEBRIS IS LIKELY THE RESULT OF THE RECENT IN ORBIT COLLISION OF TWO
SATELLITES ON TUESDAY...FEBRUARY 10TH WHEN KOSMOS 2251 CRASHED INTO
IRIDIUM 33.

That’s pretty amazing.

Update: Well, it would be if it were true.  Turns out it’s just meteors.

As you were.

Boom!

Thursday, February 12th, 2009

I know that space debris is a real and worsening problem, but I have to admit that my first reaction to hearing that two satellites had just collided was “Cool!”

Britain envy

Saturday, February 7th, 2009

There’s nothing in US journalism anything like Ben Goldacre’s Bad Science columns for the Guardian.  Check them out.  The point of the column is to tear into bad science and especially bad science reporting.  He writes with humor (or is it humour?) and attitude.  He’s not afraid to get a bit technical (although with great clarity, I think) when the situation calls for it.

In a way, he has nothing to complain about: he lives in a country with both the Guardian and the Economist, which have much better science reporting than anything we’ve got here.

Science and stimulus

Friday, February 6th, 2009

The Senate is considering removing a bunch of science funding from the stimulus package.  I don’t pretend to know much about the economics, and I freely admit that as someone who gets funded by NSF I have an interest in this, but still I’d like to argue that removing these funds is a bad idea.

You want shovel-ready?  It’s hard to get much more shovel-ready than an NSF grant.  A lot of the money in a typical grant goes to fund jobs for several people, including students and postdocs, who will start work pretty much right away.  Some goes to equipment, which again will start to be spent pretty quickly.

Some of the money goes to overhead for the host institution.  When that’s a public university, that’s a great outcome too, as these universities are going to be squeezed by state budget cuts and an increase in students taking shelter from the job market. In the case where the host institution is a rich private university, I’ll grant that sending overhead there isn’t necessarily the highest priority, although it’s far from the worst thing you can do with the money.  Anyway, public universities that really need the money far outweigh rich private schools that don’t.

In addition to being shovel-ready, of course you want the money to go to worthwhile things.  I’ll just point out that a strong case can be made that funding basic science is an investment that pays back in future economic growth.

Finally, let me point out that there are a lot of great grant proposals being submitted to the funding agencies that are denied, not for lack of merit but for lack of funds.  The first link above says that 1/4 of NSF proposals are funded.  I’ve been on several grant review panels in the past few years, and it’s always been more like 1/6.  Believe me, there are a lot of extremely worthy ideas in some of the unfunded 5/6 of the proposals.

Now’s a good time to write and call your senator to let them know what you think about science funding.  People I’ve talked to in Washington say that calls like this really do make a difference. If you’re in Virginia, your senators are Mark Warner (202-224-2023) and Jim Webb (202-224-4024).  If you’re not in Virginia, you can look up how to contact your senators.

Update: The compromise bill passed by the Senate includes most of the original science funding.

If you have nothing better to do …

Sunday, February 1st, 2009

You can come hear me give a talk on “Listening to the Big Bang” at the Science Museum of Virginia this coming Wednesday at noon.  It’s part of their Lunch Break Science series.