Number 67 in the ‘top science stories of the year’ in Discover Magazine is entitled ‘U.S. Science Supremacy Threatened by Competition’. Some interesting facts: according to the National Science Board, an independent policy group that advises the president and the congress,
the drop in foreign applications – down 28 percent at the graduate level – is (…) certain to affect the future of science. Many who come here to study do not return to their native countries. A survey by the National Science Foundation in 2000 reported that 38 percent of U.S. scientists with doctorates were born abroad.
Also:
the number of research articles by Americans has been stagnant compared with an increasing number written by Western Europeans in the last decade.
Bought the third edition of “Statistics and Data Analysis in Geology” by John C. Davis – a lot of it looks familiar, but it’s good to have this on the shelf. I like the good old citation at the beginning from Lord Kelvin — I have seen it several times before, but it still sounds important:
“…when you can measure what you are speaking about and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of science, whatever the matter may be.”
Back again to power laws. After some more googling, I found an even more important piece of blogging by Cosma Shalizi: Speaking Truth to Power About Weblogs, or, How Not to Draw a Straight Line. The title says it all: just don’t play with power law distributions by fitting straight lines to log-log plots, because chances are that you will get a reasonably looking line and R squared will be relatively large, but that still does not mean that there is a power law distribution. Shalizi is complaining about papers in statistical physics and complexity theory that do such things — well, he should see what is going on in sedimentary geology, where somebody invented the ‘segmented power-law distributions’ and now everybody who is measuring bed thicknesses is fitting not one, but two or even more straight lines to log-log plots of cumulative distributions. It’s utter nonsense, even more so than with a single straight line, but it looks very sophisticated and regular, and people keep doing these plots and all kinds of fancy interpretations based on them (earthquakes, self-organizing criticality, confinement, erosion, etc.). If it plots as a straight line – fine, it’s a power law, we explained everything. If it does not plot as a straight line — well, just fit two straight lines and talk about two populations, and how the original power-law distribution has been modified by erosion, confinement, etc. – and we explained everything again. I know I am also guilty of some of this in my thesis, but at least I have never done the segmented power law plots.
Just for the records: here is a link to my paper in Sedimentology. Overall I am fairly happy with it, I haven’t changed my mind about most of the things I have written about in this paper, unlike with many other subjects I have done some work on.
Did a bit of reading today on power law distributions, just to refresh my memories from three years ago when I was writing my thesis. And found some interesting papers and notes on the web, e.g., this one. I think we are still far from being able to use bed thickness distributions in a useful, predictive way, even though this has become a popular subject among turbidite experts. One of the problems is that it is easy to play with the distributions (e.g., take an initial power-law distribution and modify it by amalgamation), but things are probably a lot more complicated and cannot be explained just with amlagamation and basin topography. The other problem is that power-law distributions and their exponents cannot be assessed by fitting a straight line to an exceedence probability plot, as it is explained here. This method is bound to give erroneous estimates when dealing with a single distribution, but it is close to meaningless when people want to break out two different populations by fitting not one, but two lines to the exceedence probability plot.
Well, I guess that is enough about power laws for today.
Richard Dawkins is the first on the list of the top 100 public intellectuals of Britain, as voted by readers of Prospect Magazine. Yess!
Found a good quotation from philosopher Simon Blackburn on “Butterflies and Wheels“. Originally it appeared in the Oxford Dictionary of Philosophy, in the “Postmodernism” entry:
While the dismantling of objectivity seems to some to be the way towards a liberating political radicalism, to others it allows such unliberating views as the denial that there was (objectively) such an event as the Second World War or the Holocaust…The postmodernist frame of mind…may seem to depend on a cavalier dismissal of the success of science in generating human improvement, an exaggeration of the admitted fallibility of any attempt to gain knowledge in the humane disciplines, and an ignoring of the quite ordinary truth that while human history and law admit of no one final description, they certainly admit of more or less accurate ones…
Going back to Freud (see the last entry): here is some supporting material for the claim that Freud
belongs more in a museum of errors, with studies of the four humours, the benefits of blood-letting, pre-Copernican astronomy, the forensics of witchcraft, alchemy, phrenology and phlogiston.
Finished reading two books by Steven Johnson: Emergence and Mind Wide Open. The latter is fresher. Quite liked it overall, although it does not feel as enlightening as Richard Dawkins or Steven Pinker often do. But then, this might be too high of a measuring stick.
In the final chapter of Mind Wide Open, S. Johnson paints a bit too positive picture of Freud. Maybe it is a great insight indeed that the mind is divided, but it looks to me that there are a lot more misses than hits in the freudian view of the mind. It is a little bit like saying that the geosynclinal theory is very important because it got a few things right: sediments often do accumulate in big piles several miles thick and then become parts of folded mountain ranges. Well, that’s true, but there is no explanatory power to it — for that, you need modern plate tectonics and basin analysis. So, isn’t it easier to just forget old and wrong concepts like id, superego, and miogeoclines?
Hindered Settling 