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Posts

May 04, 2015

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5:00 AM | Phase Transition of Joint-Sparse Recovery from Multiple Measurements Via Convex Optimization
On January 22, 2014, I wondered whether there was much progress in the phase transition for MMV type of problems as it had a direct bearing on our paper on Compressive Imaging Using a Multiply Scattering Medium: It turrned out, that  Jeff Blanchard, Michael Cermak, David Hanle and, Yirong Jing had laready provided an answer in Greedy Algorithms for Joint Sparse Recovery.  Later Jared Tanner mentioned further work in that direction.featured in CGIHT: Conjugate Gradient Iterative Hard […]
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2:30 AM | Briefly
From the Guardian, in an otherwise-sensible piece talking about decreases in infant mortality “So things are getting better. The small wrinkly proto-Royal that just emerged from the national womb will have thrice the chance of surviving that her father and I did, just through the privilege of being born in 2015.” It’s pretty obvious this is […]
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2:09 AM | Inventor of Arxiv speaks at Columbia this Tues 4pm
Paul Ginsparg, professor of physics at Cornell University and inventor of Arxiv, is speaking Tuesday 5 May, 4pm in CEPSR 750. Here’s the abstract: I [Ginsparg] will give a very brief sociological overview of the current metastable state of scholarly research communication, and then a technical discussion of the practical implications of literature and usage […] The post Inventor of Arxiv speaks at Columbia this Tues 4pm appeared first on Statistical Modeling, Causal Inference, and […]

May 03, 2015

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10:40 PM | Things I Don’t Get, Part the Eleventy-Billionth
It always baffles me when people think The Incredibles is an Objectivist movie. It examines, under the surface of an adventure story, the psychological foibles which can lead people into Randroidism. That’s a very different animal. But some people seem to take “When everyone is special, no one will be” as the movie’s actual moral. … Continue reading Things I Don’t Get, Part the Eleventy-Billionth →
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8:00 PM | Stat of the Week Competition: May 2 – 8 2015
Each week, we would like to invite readers of Stats Chat to submit nominations for our Stat of the Week competition and be in with the chance to win an iTunes voucher. Here’s how it works: Anyone may add a comment on this post to nominate their Stat of the Week candidate before midday Friday […]
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8:00 PM | Stat of the Week Competition Discussion: May 2 – 8 2015
If you’d like to comment on or debate any of this week’s Stat of the Week nominations, please do so below!
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4:58 PM | Virial theorem for gravitational orbits
Reference: Carroll, Bradley W. & Ostlie, Dale A. (2007), An Introduction to Modern Astrophysics, 2nd Edition; Pearson Education – Chapter 2, Problems 2.9, 2.10. We’ve already met the virial theorem in quantum mechanics where it had the form, in one dimension: where is the kinetic energy and is the potential energy. Applying this to an […]
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1:10 PM | Forget about pdf: this looks much better, it makes all my own papers look like kids’ crayon drawings by comparison.
Mark Palko points me to this webpage which presents a recent research paper by Joanna Shepherd and Michael Kang. I have no comment on the research—I haven’t had a chance to read the paper—but I wanted to express how impressed I was about the presentation. It starts with a dedicated url just for this paper […] The post Forget about pdf: this looks much better, it makes all my own papers look like kids’ crayon drawings by comparison. appeared first on Statistical […]
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7:13 AM | What’s the right proof of the Continuous Mapping Theorem?
The Continuous Mapping Theorem says that if $X_n\stackrel{d}{\to}X$ and $f$ is continuous except at a set of points with zero probability under $X$, that $f(X_n)\stackrel{d}{\to}f(X)$.  As David Pollard points out, it should be called the almost-everywhere-continuous mapping theorem, because the ability to have discontinuities is important in applications and is the only thing making the proof non-trivial. There are three proofs that I’m aware ofMann and Wald used the ‘pointwise […]

May 02, 2015

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6:30 PM | blowup of the projective plane ℙ² by Charles Staats HT...
blowup of the projective plane ℙ² by Charles Staats HT @hdevalence
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3:19 PM | Kepler’s third law and satellite orbits
Reference: Carroll, Bradley W. & Ostlie, Dale A. (2007), An Introduction to Modern Astrophysics, 2nd Edition; Pearson Education – Chapter 2, Problem 2.8. From Kepler’s third law, we can work out some facts about satellite orbits around the Earth. The law is where is the period, is the semimajor axis and is the total mass […]
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2:15 PM | Aunt Pythia’s advice
People! PEOPLE! Aunt Pythia needs your help!! Here’s the thing, dear readers. Aunt Pythia screwed up royally. She told you a couple of weeks back that she had plenty of questions, and in a sense she did, but that was misleading, and moreover it has backfired tremendously. You see, Aunt Pythia finally read all those […]
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1:10 PM | Which of these classes should he take?
Jake Humphries writes: I for many years wanted to pursue medicine but after recently completing a master of public health, I caught the statistics bug. I need to complete the usual minimum prerequisites for graduate study in statistics (calculus through multivariable calculus plus linear algebra) but want to take additional math courses as highly competitive […] The post Which of these classes should he take? appeared first on Statistical Modeling, Causal Inference, and Social Science.
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5:30 AM | Saturday Morning Videos: IMA Workshop on Convexity and Optimization: Theory and Applications February 23-27, 2015
  IMA Workshop on Convexity and Optimization: Theory and Applications February 23-27, 2015 Presentation of the workshop:The workshop will consist of two parts. Day one will cover supply chain optimization with the objective of bringing together leading researchers/developers from industry with leading researchers from academia to discuss challenges, opportunities, and new trends in logistics, material handling, optimization, machine learning, and related algorithms. The second […]
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5:00 AM | Saturday Morning Videos: IMA / AP Workshop: Information Theory and Concentration Phenomena April 13-17, 2015
Here are the videos of the IMA /AP Workshop: Information Theory and Concentration Phenomenathat took place on April 13-17, 2015(IMA webmaster: please note that this video is that of Andrea Montanari not Victoria Kostina)Presentation of the workshop:Concentration phenomena have come to play a significant role in probability, statistics, and computer science. The purpose of this workshop is to bring together applied and theoretical researchers to stimulate further progress on concentration […]

May 01, 2015

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9:16 PM | Decorated Cospans
Last time I talked about a new paper I wrote with Brendan Fong. It’s about electrical circuits made of ‘passive’ components, like resistors, inductors and capacitors. We showed these circuits are morphisms in a category. Moreover, there’s a functor sending each circuit to its ‘external behavior': what it does, as seen by someone who can […]
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7:23 PM | Hypothesis testing is only mostly useless
In my previous article I argued that classical statistical inference is only mostly wrong. About null-hypothesis significance testing (NHST),  I wrote:“If the p-value is small, you can conclude that the fourth possibility is unlikely, and infer that the other three possibilities are more likely.”Where “the fourth possibility” I referred to was:“The apparent effect might be due to chance; that is, the difference might appear in a random sample, but not in the general […]
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6:19 PM | MFM2P - Day 56: Cup Stacking (again) & Pyramids
Today's plan: warm-up, one more cup stacking system, then move on to volume and surface area of pyramids.The warm-up was this Daily Desmos, where they have to determine the equation of the line and we check it on Desmos:I had them work in table groups on the big whiteboards. Here is some of their work:Next, I had them go around the room looking at other groups' solutions and making comments on the work. Some fixed errors while others wrote comments like "where did this come from?" and "show […]
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5:03 PM | Escape speed
Reference: Carroll, Bradley W. & Ostlie, Dale A. (2007), An Introduction to Modern Astrophysics, 2nd Edition; Pearson Education – Chapter 2, Problem 2.7. The total energy of an object of mass at a distance of from the centre of mass of another body of mass is the sum of its kinetic and gravitational potential energies, […]
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3:31 PM | Andrei Zelevinsky’s Problems
I was afraid of my advisor Israel Gelfand. He used to place unrealistic demands on me. After each seminar he would ask his students to prove by the next week any open problems mentioned by the speaker. So I got used to ignoring his requests. He also had an idea that it is good to […]
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1:53 PM | Rotating PDF pages with Python
Yesterday I got a review copy of Automate the Boring Stuff with Python. It explains, among other things, how to manipulate PDFs from Python. This morning I needed to rotate some pages in a PDF, so I decided to try out the method in the book. The sample code uses PyPDF2. I’m using Conda for […]
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1:51 PM | “The general problem I have with noninformatively-derived Bayesian probabilities is that they tend to be too strong.”
We interrupt our usual programming of mockery of buffoons to discuss a bit of statistical theory . . . Continuing from yesterday‘s quotation of my 2012 article in Epidemiology: Like many Bayesians, I have often represented classical confidence intervals as posterior probability intervals and interpreted one-sided p-values as the posterior probability of a positive effect. […] The post “The general problem I have with noninformatively-derived Bayesian probabilities is that they […]
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1:29 PM | In defense of dowdy
I’ve been thinking recently about the definition of “civilization.” What makes a society civilized? I have some guesses, here are a few guesses, kind of in order of obviousness: A place where grown men don’t get harassed when they walk around minding their own business. I’m looking at you, broken windows policies. A place where young […]
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11:13 AM | A rich person's idea of a poor person's grocery
I had actually forgotten how on-topic this video was. As mentioned before, there's a thread coming up on hunger in this country prompted by yet another journalist who would apparently drop dead of malnutrition if she had to live on a budget for an extended period.A big part of this story is the way different classes perceive budgets and shopping and the way most journalists have internalized upper and upper-middle class perceptions. It's telling that when a journalist had to find the cheapest […]
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10:41 AM | Arrival in Bretzenheim
Since I moved to Mainz two years ago my wife has remained in Berlin and we have been searching for a suitable place to live in Mainz or its surroundings. The original plan was to buy a piece of land on which we could build a house. This turned out to be much more difficult […]
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8:37 AM | If it seems too good to be true
This one is originally from the Telegraph, but it’s one where you might expect the local editors to exercise a little caution in reposting it A test that can predict with 100 per cent accuracy whether someone will develop cancer up to 13 years in the future has been devised by scientists. It’s very unlikely that the accuracy […]
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7:17 AM | Parametric Inference: The Power Function of the Test
In Statistics, we model random phenomenon and make conclusions about its population. For example, in an experiment of determining the true heights of the students in the university. Suppose we take sample from the population of the students, and consider testing the null hypothesis that the average height is 5.4 ft against an alternative hypothesis that the average height is greater than 5.4 ft. Mathematically, we can represent this as $H_0:\theta=\theta_0$ vs $H_1:\theta>\theta_0$, where […]
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5:01 AM | Linkage
Some good discussions this time over on G+, especially for the vote-off-the-island post but also on the golden spiral, P=NP counterexample, and election-system posts.3d rendered art by Joey Camacho (G+)Rivers don't actually approximate semicircles (G+)Intimidating researchers from discussing known vulnerabilities in fly-by-wire systems (G+)ICALP accepted papers (G+)Animations of mechanical linkages (G+)If impact factors are so obviously irrelevant, why do we still use them? (G+)California MOOC […]
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5:00 AM | Nuit Blanche in Review ( April 2015 )
NASA / JHUAPL / SwRIIn the past month, we witness the first images of Pluto with a resolution never attained before thanks to thr New Horizon mission  and the crash of the Messenger spacecraft on Mercury.Well I guess it is time to say goodbye to all my friends, family, support team. I will be making my final impact very soon.— MESSENGER (@MESSENGER2011) April 30, 2015 Since the last  Nuit Blanche in Review ( March 2015 ) we had quite a few hardware related papers:Task-driven […]
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4:00 AM | Calculus at Crisis I: The Pressures
By David BressoudCrisis: A decisive moment. The choice of preposition in the title of this new series is intentional. To be “in crisis” indicates a desperate situation that is not sustainable. I have chosen “at crisis” to indicate a degenerating situation that calls for decisive change. I will begin this series with an account of some of the pressures that have brought us to this pass.In February of 2012, the President’s Council of Advisors on Science and Technology (PCAST) produced a […]
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