“Page Weight Matters” (Simpson’s paradox: when a better treatment—faster YouTube page loads—makes aggregate numbers worse (average latency goes up) because new users arrive due to the improvement)
The Martian (a faithful but very Hollywood depiction of the novel; it is exactly what one would expect upon hearing that The Martian was being turned into a big-budget film starring Matt Damon & Sigourney Weaver, glossy special effects and overwrought soundtrack and all. What is cut from the novel was of no importance.)
This page is a changelog for Gwern.net: a monthly reverse chronological list of recent major writings/changes/additions.
Following my writing can be a little difficult because it is often so incremental. So every month, in addition to my regular /r/Gwern subreddit submissions, I write up reasonably-interesting changes and send it out to the mailing list in addition to a compilation of links & reviews (archives).
A subreddit for posting links of interest and also for announcing updates to gwern.net (which can be used as a RSS feed). Submissions are categorized similar to the monthly newsletter and typically will be collated there.
Mail is delivered by the USPS mailman at a regular but not observed time; what is observed is whether the mail has been delivered at a time, yielding somewhat-unusual “interval-censored data”. I describe the problem of estimating when the mailman delivers, write a simulation of the data-generating process, and demonstrate analysis of interval-censored data in R using maximum-likelihood (survival analysis with Gaussian regression using survival library), MCMC (Bayesian model in JAGS), and likelihood-free Bayesian inference (custom ABC, using the simulation). This allows estimation of the distribution of mail delivery times. I compare those estimates from the interval-censored data with estimates from a (smaller) set of exact delivery-times provided by USPS tracking & personal observation, using a multilevel model to deal with heterogeneity apparently due to a change in USPS routes/postmen. Finally, I define a loss function on mail checks, enabling: a choice of optimal time to check the mailbox to minimize loss (exploitation); optimal time to check to maximize information gain (exploration); Thompson sampling (balancing exploration & exploitation indefinitely), and estimates of the value-of-information of another datapoint (to estimate when to stop exploration and start exploitation after a finite amount of data).
Estimating the cost to society of individual crimes is essential to the economic evaluation of many social programs, such as substance abuse treatment and community policing. A review of the crime-costing literature reveals multiple sources, including published articles and government reports, which collectively represent the alternative approaches for estimating the economic losses associated with criminal activity. Many of these sources are based upon data that are more than 10 years old, indicating a need for updated figures. This study presents a comprehensive methodology for calculating the cost to society of various criminal acts. Tangible and intangible losses are estimated using the most current data available. The selected approach, which incorporates both the cost-of-illness and the jury compensation methods, yields cost estimates for more than a dozen major crime categories, including several categories not found in previous studies. Updated crime cost estimates can help government agencies and other organizations execute more prudent policy evaluations, particularly benefit-cost analyses of substance abuse treatment or other interventions that reduce crime.
Comparative studies of the brain in mammals suggest that there are general architectural principles governing its growth and evolutionary development. We are beginning to understand the geometric, biophysical and energy constraints that have governed the evolution and functional organization of the brain and its underlying neuronal network. The object of this review is to present current perspectives on primate brain evolution, especially in humans, and to examine some hypothetical organizing principles that underlie the brain's complex organization. Some of the design principles and operational modes that underlie the information processing capacity of the cerebral cortex in primates will be explored. It is shown that the development of the cortex coordinates folding with connectivity in a way that produces smaller and faster brains, then otherwise would have been possible. In view of the central importance placed on brain evolution in explaining the success of our own species, one may wonder whether there are physical limits that constrain its processing power and evolutionary potential. It will be argued that at a brain size of about 3500 cm(3), corresponding to a brain volume two to three times that of modern man, the brain seems to reach its maximum processing capacity. The larger the brain grows beyond this critical size, the less efficient it will become, thus limiting any improvement in cognitive power.
Visual release hallucinations, also known as Charles Bonnet syndrome or CBS, are a type of psychophysical visual disturbance and the experience of complex visual hallucinations in a person with partial or severe blindness.
In conclusion, fencing tempo is a vital element of swordsmanship, but clearly for the duelist hitting before being hit is not at all the same thing as hitting without being hit. Exsanguination is the principal mechanism of death caused by stabbing and incising wounds and death by this means is seldom instantaneous. Although stab wounds to the heart are generally imagined to be instantly incapacitating, numerous modern medical case histories indicate that while victims of such wounds may immediately collapse upon being wounded, rapid disability from this type of wound is by no means certain. Many present-day victims of penetrating wounds involving the lungs and the great vessels of the thorax have also demonstrated a remarkable ability to remain physically active minutes to hours after their wounds were inflicted. These cases are consistent with reports of duelists who, subsequent to having been grievously or even mortally wounded through the chest, neck, or abdomen, nevertheless remained actively engaged upon the terrain and fully able to continue long enough to dispatch those who had wounded them.
…Early American motion pictures have frequently misrepresented virtually every aspect of authentic swordplay. This seems to have been especially true of the industry’s depiction of the manner in which swordsmen fell before the blades of their opponents. While anecdotes of duels may have been biased by politics or personal vanity, modern forensic medicine provides ample evidence to support historical accounts of gravely wounded duelists continuing in combats for surprising lengths of time, sometimes killing those who had killed them.
In the first installment of this essay modern forensic evidence indicated that exsanguination is the principal mechanism of death caused by stabbing and incising wounds, but that death by this means is seldom instantaneous; victims frequently capable of continued physical activity, even after being stabbed in the heart. Similarly, victims of sharp force injuries to the lungs are not infrequently able to carry on for protracted periods of time. Wounds which result in the introduction of blood into the upper airway, on the other hand, are likely to incapacitate and kill an adversary quite rapidly.
Duels featuring penetrating wounds to the muscles of the sword arm appear in some cases to have left duelists fully capable of manipulating their weapons. Thrusts to the thigh and leg may have been even less efficacious. Strokes with the cutting edges of swords to the limbs may result in more serious wounds to the musculature than the penetrating variety, but historical accounts of duels demonstrate that immediate incapacitation of an adversary stricken with such wounds was by no means guaranteed. Incising wounds which sever tendons, however, can be expected to immediately incapacitate the muscles from which they arise. Recent medical reports of sharp force injuries to the brain suggest that even a sword-thrust penetrating the skull ought not to have been expected always to disable an opponent instantaneously. While severe pain is usually incapacitating, the stress of combat may mask the pain of gravely serious wounds, enabling the determined duelist to remain on the ground for a considerable length of time.
The immediate consequences to a duelist of wounds inflicted by thrusts or cuts from the rapier, dueling sabre or smallsword were unpredictable. While historical anecdotes of affairs of honor and twentieth century medical reports show that many stabbing victims collapsed immediately upon being wounded, others did not. While a swordsman certainly gained no advantage for having been wounded, it cannot be said that an unscathed adversary, after having delivered a fatal thrust or cut, had no further concern for his safety. Duelists receiving serious and even mortal wounds were sometimes able to continue effectively in the combat long enough to take the lives of those who had taken theirs…For the duelist, however, another form of tempo had to be considered. In the early history of affairs of honor, this “dueling tempo” spanned the period extending from the moment that a wound was inflicted until the instant that the adversary was no longer able to continue effectively. This span of time was unpredictable in length and could be expressed in terms ranging from a fraction of a second to minutes. Considering the number and severity of wounds that were sustained by combatants in the early days of the duel, it would not be surprising to find that many duelists of latter days secretly breathed a sigh of relief when interrupted by seconds rushing in to terminate affairs of honor immediately upon the delivery of a well placed cut or thrust.
We study the out-of-sample and post-publication return predictability of 97 variables shown to predict cross-sectional stock returns. Portfolio returns are 26% lower out-of-sample and 58% lower post-publication. The out-of-sample decline is an upper bound estimate of data mining effects. We estimate a 32% (58%–26%) lower return from publication-informed trading. Post-publication declines are greater for predictors with higher in-sample returns, and returns are higher for portfolios concentrated in stocks with high idiosyncratic risk and low liquidity. Predictor portfolios exhibit post-publication increases in correlations with other published-predictor portfolios. Our findings suggest that investors learn about mispricing from academic publications.
The Great Gatsby is a 1925 novel by American writer F. Scott Fitzgerald. Set in the Jazz Age on Long Island, the novel depicts narrator Nick Carraway's interactions with mysterious millionaire Jay Gatsby, and Gatsby's obsession to reunite with his former lover, Daisy Buchanan.
The Martian is a 2015 science fiction film directed by Ridley Scott and starring Matt Damon. The Martian, a 2011 novel by Andy Weir, served as the screenplay adapted by Drew Goddard. The film depicts an astronaut's lone struggle to survive on Mars after being left behind, and efforts to rescue him and bring him home to Earth. It also stars Jessica Chastain, Jeff Daniels, Kristen Wiig, Chiwetel Ejiofor, Sean Bean, Michael Peña, Kate Mara, Sebastian Stan, Aksel Hennie, Mackenzie Davis, Donald Glover, and Benedict Wong.
The Great Gatsby is a 2013 romantic drama film based on F. Scott Fitzgerald's 1925 novel of the same name. The film was co-written and directed by Baz Luhrmann and stars Leonardo DiCaprio as the eponymous Jay Gatsby, with Tobey Maguire, Carey Mulligan, Joel Edgerton, Isla Fisher, Jason Clarke, Elizabeth Debicki and Jack Thompson. Jay-Z served as executive producer. Production began in 2011 and took place in Australia, with a $105 million net production budget. The film follows the life and times of millionaire Jay Gatsby (DiCaprio) and his neighbor Nick Carraway (Maguire), who recounts his encounter with Gatsby at the height of the Roaring Twenties on Long Island.
Back to the Future Part II is a 1989 American science fiction film directed by Robert Zemeckis and written by Bob Gale. It is the sequel to the 1985 film Back to the Future and the second installment in the Back to the Future trilogy. The film stars Michael J. Fox, Christopher Lloyd, Lea Thompson, and Thomas F. Wilson. The film follows Marty McFly (Fox) and his friend Dr. Emmett "Doc" Brown (Lloyd) as they travel from 1985 to 2015 to prevent Marty's son from sabotaging the McFly family's future; when their arch-nemesis Biff Tannen (Wilson) steals Doc's DeLorean time machine and uses it to alter history for his benefit, the duo must return to 1955 to restore the timeline.
A Letter to Momo is a 2011 Japanese anime drama film produced by Production I.G and distributed by Kadokawa Pictures. The film was written and directed by Hiroyuki Okiura and stars an ensemble cast featuring Karen Miyama, Yuka, Toshiyuki Nishida, Chō and Kōichi Yamadera. In A Letter to Momo, 11-year-old Momo Miyaura moves with her mother to a small island town after her father dies. When she arrives, she encounters three goblins that others cannot see who help her to cope with the loss of her father and the changes in her life.
Subscription page for the monthly gwern.net newsletter. There are monthly updates, which will include summaries of projects I’ve worked on that month (the same as the changelog), collations of links or discussions from my subreddit, and book/movie reviews. You can also browse the archives since December 2013.
Newsletter tag: archive of all issues back to 2013 for the gwern.net newsletter (monthly updates, which will include summaries of projects I’ve worked on that month (the same as the changelog), collations of links or discussions from my subreddit, and book/movie reviews.)