Skip to main content

meta directory

Links

“Lorem Ipsum”, Branwen 2020

Lorem: “Lorem Ipsum”⁠, Gwern Branwen (2020-09-27; ⁠, ⁠, ⁠, ; similar):

Systems stress-test page for Gwern.net functionality, exercising Markdown/​HTML/​CSS/​JS features at scale to check that they render correctly in mobile/​desktop.

Abstract of article summarizing the page. For design philosophy, see About⁠. This is a test page which exercises all standard functionality and features of Gwern.net, from standard Pandoc Markdown like blockquotes/​headers/​tables/​images, to custom features like sidenotes, margin notes, left/​right-floated and width-full images, columns, epigraphs, admonitions, small/​wide tables, smallcaps, collapse sections, link annotations, link icons.

User-visible bugs which may appear on this page: zooms into small rather than large original image (mobile).

“Catnip Immunity and Alternatives”, Branwen 2015

Catnip: “Catnip immunity and alternatives”⁠, Gwern Branwen (2015-11-07; ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Estimation of catnip immunity rates by country with meta-analysis and surveys, and discussion of catnip alternatives.

Not all cats respond to the catnip stimulant; the rate of responders is generally estimated at ~70% of cats. A meta-analysis of catnip response experiments since the 1940s indicates the true value is ~62%. The low quality of studies and the reporting of their data makes examination of possible moderators like age, sex, and country difficult. Catnip responses have been recorded for a number of species both inside and outside the Felidae family; of them, there is evidence for a catnip response in the Felidae, and, more uncertainly, the Paradoxurinae, and Herpestinae.

To extend the analysis, I run large-scale online surveys measuring catnip response rates globally in domestic cats, finding high heterogeneity but considerable rates of catnip immunity worldwide.

As a piece of practical advice for cat-hallucinogen sommeliers, I treat catnip response & finding catnip substitutes as a decision problem, modeling it as a Markov decision process where one wishes to find a working psychoactive at minimum cost. Bol et al 2017 measured multiple psychoactives simultaneously in a large sample of cats, permitting prediction of responses conditional on not responding to others. (The solution to the specific problem is to test in the sequence catnip → honeysuckle → silvervine → Valerian⁠.)

For discussion of cat psychology in general, see my Cat Sense review.

“The Sort --key Trick”, Branwen 2014

Sort: “The sort --key Trick”⁠, Gwern Branwen (2014-03-03; ⁠, ⁠, ⁠, ; backlinks; similar):

Commandline folklore: sorting files by filename or content before compression can save large amounts of space by exposing redundancy to the compressor. Examples and comparisons of different sorts.

Programming folklore notes that one way to get better lossless compression efficiency is by the precompression trick of rearranging files inside the archive to group ‘similar’ files together and expose redundancy to the compressor, in accordance with information-theoretical principles. A particularly easy and broadly-applicable way of doing this, which does not require using any unusual formats or tools and is fully compatible with the default archive methods, is to sort the files by filename and especially file extension.

I show how to do this with the standard Unix command-line sort tool, using the so-called “sort --key trick”, and give examples of the large space-savings possible from my archiving work for personal website mirrors and for making darknet market mirror datasets where the redundancy at the file level is particularly extreme and the sort --key trick shines compared to the naive approach.

“Changelog”, Branwen 2013

Changelog: “Changelog”⁠, Gwern Branwen (2013-09-15; similar):

Monthly chronological list of recent major writings/​changes/​additions to Gwern.net (see also the monthly newsletter).

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 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).

“Creatine Cognition Meta-analysis”, Branwen 2013

Creatine: “Creatine Cognition Meta-analysis”⁠, Gwern Branwen (2013-09-06; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Does creatine increase cognitive performance? Maybe for vegetarians but probably not.

I attempt to meta-analyze conflicting studies about the cognitive benefits of creatine supplementation. The wide variety of psychological measures by uniformly small studies hampers any aggregation. 3 studies measured IQ and turn in a positive result, but suggestive of vegetarianism causing half the benefit. Discussions indicate that publication bias is at work. Given the variety of measures, small sample sizes, publication bias, possible moderators, and small-study biases, any future creatine studies should use the most standard measures of cognitive function like RAPM in a reasonably large pre-registered experiment.

“A/B Testing Long-form Readability on Gwern.net”, Branwen 2012

AB-testing: “A/B testing long-form readability on Gwern.net”⁠, Gwern Branwen (2012-06-16; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

A log of experiments done on the site design, intended to render pages more readable, focusing on the challenge of testing a static site, page width, fonts, plugins, and effects of advertising.

To gain some statistical & web development experience and to improve my readers’ experiences, I have been running a series of CSS A/​B tests since June 2012. As expected, most do not show any meaningful difference.

“Dual N-Back Meta-Analysis”, Branwen 2012

DNB-meta-analysis: “Dual n-Back Meta-Analysis”⁠, Gwern Branwen (2012-05-20; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Does DNB increase IQ? What factors affect the studies? Probably not: gains are driven by studies with weakest methodology like apathetic control groups.

I meta-analyze the >19 studies up to 2016 which measure IQ after an n-back intervention, finding (over all studies) a net gain (medium-sized) on the post-training IQ tests.

The size of this increase on IQ test score correlates highly with the methodological concern of whether a study used active or passive control groups⁠. This indicates that the medium effect size is due to methodological problems and that n-back training does not increase subjects’ underlying fluid intelligence but the gains are due to the motivational effect of passive control groups (who did not train on anything) not trying as hard as the n-back-trained experimental groups on the post-tests. The remaining studies using active control groups find a small positive effect (but this may be due to matrix-test-specific training, undetected publication bias, smaller motivational effects, etc.)

I also investigate several other n-back claims, criticisms, and indicators of bias, finding:

“Iodine and Adult IQ Meta-analysis”, Branwen 2012

Iodine: “Iodine and Adult IQ meta-analysis”⁠, Gwern Branwen (2012-02-29; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Iodine improves IQ in fetuses; adults as well? A meta-analysis of relevant studies says no.

Iodization is one of the great success stories of public health intervention: iodizing salt costs pennies per ton, but as demonstrated in randomized & natural experiments, prevents goiters, cretinism, and can boost population IQs by a fraction of a standard deviation in the most iodine-deficient populations.

These experiments are typically done on pregnant women, and results suggest that the benefits of iodization diminish throughout the trimesters of a pregnancy. So does iodization benefit normal healthy adults, potentially even ones in relatively iodine-sufficient Western countries?

Compiling existing post-natal iodization studies which use cognitive tests, I find that—outliers aside—the benefit appears to be nearly zero, and so likely it does not help normal healthy adults, particularly in Western adults.

“Archiving URLs”, Branwen 2011

Archiving-URLs: “Archiving URLs”⁠, Gwern Branwen (2011-03-10; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Archiving the Web, because nothing lasts forever: statistics, online archive services, extracting URLs automatically from browsers, and creating a daemon to regularly back up URLs to multiple sources.

Links on the Internet last forever or a year, whichever comes first. This is a major problem for anyone serious about writing with good references, as link rot will cripple several% of all links each year, and compounding.

To deal with link rot, I present my multi-pronged archival strategy using a combination of scripts, daemons, and Internet archival services: URLs are regularly dumped from both my web browser’s daily browsing and my website pages into an archival daemon I wrote, which pre-emptively downloads copies locally and attempts to archive them in the Internet Archive⁠. This ensures a copy will be available indefinitely from one of several sources. Link rot is then detected by regular runs of linkchecker, and any newly dead links can be immediately checked for alternative locations, or restored from one of the archive sources.

As an additional flourish, my local archives are efficiently cryptographically timestamped using Bitcoin in case forgery is a concern, and I demonstrate a simple compression trick for substantially reducing sizes of large web archives such as crawls (particularly useful for repeated crawls such as my DNM archives).

“Gwern.net Website Traffic”, Branwen 2011

Traffic: “Gwern.net Website Traffic”⁠, Gwern Branwen (2011-02-03; ⁠, ⁠, ⁠, ⁠, ; similar):

Meta page describing Gwern.net editing activity, traffic statistics, and referrer details, primarily sourced from Google Analytics (2011-present).

On a semi-annual basis, since 2011, I review Gwern.net website traffic using Google Analytics; although what most readers value is not what I value, I find it motivating to see total traffic statistics reminding me of readers (writing can be a lonely and abstract endeavour), and useful to see what are major referrers.

Gwern.net typically enjoys steady traffic in the 50–100k range per month, with occasional spikes from social media, particularly Hacker News; over the first decade (2010–2020), there were 7.98m pageviews by 3.8m unique users.

“The Replication Crisis: Flaws in Mainstream Science”, Branwen 2010

Replication: “The Replication Crisis: Flaws in Mainstream Science”⁠, Gwern Branwen (2010-10-27; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

2013 discussion of how systemic biases in science, particularly medicine and psychology, have resulted in a research literature filled with false positives and exaggerated effects, called ‘the Replication Crisis’.

Long-standing problems in standard scientific methodology have exploded as the “Replication Crisis”: the discovery that many results in fields as diverse as psychology, economics, medicine, biology, and sociology are in fact false or quantitatively highly inaccurately measured. I cover here a handful of the issues and publications on this large, important, and rapidly developing topic up to about 2013, at which point the Replication Crisis became too large a topic to cover more than cursorily. (A compilation of some additional links are provided for post-2013 developments.)

The crisis is caused by methods & publishing procedures which interpret random noise as important results, far too small datasets, selective analysis by an analyst trying to reach expected/​desired results, publication bias, poor implementation of existing best-practices, nontrivial levels of research fraud, software errors, philosophical beliefs among researchers that false positives are acceptable, neglect of known confounding like genetics, and skewed incentives (financial & professional) to publish ‘hot’ results.

Thus, any individual piece of research typically establishes little. Scientific validation comes not from small p-values, but from discovering a regular feature of the world which disinterested third parties can discover with straightforward research done independently on new data with new procedures—replication.

“Lithium in Ground-water and Well-being”, Branwen 2010

Lithium: “Lithium in ground-water and well-being”⁠, Gwern Branwen (2010-10-14; ⁠, ⁠, ; backlinks; similar):

Lithium is a well-known mood stabilizer & suicide preventive; some research suggests lithium may be a cognitively-protective nutrient and at the population level, chronic lithium consumption (through drinking water) predicts lower levels of mental illness, violence, & suicide.

The metal lithium is a well-known mood stabilizer & suicide preventive widely used in psychiatry. It is also a trace mineral present to various levels in all drinking water and much food. A long-running but obscure vein of research speculates on whether lithium is beneficial and a nutrient, specifically, cognitively-protective. Epidemiological research has correlated chronic lithium consumption through drinking water with a number of population-level variables like rates of mental illness, violence, & suicide. If causal, lithium should be regarded as a vital nutrient for mental health and added to drinking water to substantially improve population-wide outcomes.

However, the evidence is weak. Most of this research is cross-sectional, only some is longitudinal, none offers particularly strong causal evidence using natural experiments or other designs, there are questions about confounding with autocorrelated spatial properties such as altitude, and some of the best research, using Scandinavian population registries, offers more mixed evaluations of claimed correlates.

It is unlikely that further such correlational research will resolve the debate, despite the mounting opportunity cost. I suggest that formal experimentation is required, and concerns about harms from lithium supplementation making experiments ‘unethical’ can be circumvented by instead removing lithium or looking for natural experiments with cause changes (such as changes or upgrades to water treatment plants or plumbing modify lithium concentration).

“Design Graveyard”, Branwen 2010

Design-graveyard: “Design Graveyard”⁠, Gwern Branwen (2010-10-01; ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Meta page describing Gwern.net website design experiments and post-mortem analyses.

Often the most interesting part of any design are the parts that are invisible—what was tried but did not work. Sometimes they were unnecessary, other times users didn’t understand them because it was too idiosyncratic, and sometimes we just can’t have nice things.

Some post-mortems of things I tried on Gwern.net but abandoned (in chronological order).

“Design Of This Website”, Branwen 2010

Design: “Design Of This Website”⁠, Gwern Branwen (2010-10-01; ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Meta page describing Gwern.net site implementation and experiments for better ‘structural reading’ of hypertext; technical decisions using Markdown and static hosting.

Gwern.net is implemented as a static website compiled via Hakyll from Pandoc Markdown and hosted on a dedicated server (due to expensive cloud bandwidth).

It stands out from your standard Markdown static website by aiming at good typography, fast performance, and advanced hypertext browsing features (at the cost of great implementation complexity); the 4 design principles are: aesthetically-pleasing minimalism, accessibility/​progressive-enhancement, speed, and a ‘structural reading’ approach to hypertext use.

Unusual features include the monochrome esthetics, sidenotes instead of footnotes on wide windows, efficient drop caps/​smallcaps, collapsible sections, automatic inflation-adjusted currency, Wikipedia-style link icons & infoboxes, custom syntax highlighting⁠, extensive local archives to fight linkrot, and an ecosystem of “popup”/​“popin” annotations & previews of links for frictionless browsing—the net effect of hierarchical structures with collapsing and instant popup access to excerpts enables iceberg-like pages where most information is hidden but the reader can easily drill down as deep as they wish. (For a demo of all features & stress-test page, see Lorem Ipsum⁠.)

Also discussed are the many failed experiments /  ​ changes made along the way.

“About This Website”, Branwen 2010

About: “About This Website”⁠, Gwern Branwen (2010-10-01; ⁠, ⁠, ⁠, ⁠, ⁠, ⁠, ; backlinks; similar):

Meta page describing Gwern.net site ideals of stable long-term essays which improve over time; idea sources and writing methodology; metadata definitions; site statistics; copyright license.

This page is about Gwern.net content; for the details of its implementation & design like the popup paradigm, see Design⁠; and for information about me, see Links⁠.

“Essays”, N/A 2009

index: “Essays”⁠, (2009-01-27; similar):

Personal website of Gwern Branwen (writer, self-experimenter, and programmer): topics: psychology, statistics, technology, deep learning, anime. This index page is a categorized list of Gwern.net pages.

This Is The Website of Gwern Branwen. I write about psychology, statistics, and technology. I am best known for work on the darknet markets & Bitcoin⁠, blinded self-experiments⁠, dual n-back & spaced repetition⁠, and anime neural networks⁠.

For information about my site’s philosophy & method, see the About page; for the website features & implementation, see the Design page; for information about myself, my use of other websites, and contact information, see the Links page; for information about new pages, see the Changelog; to receive updates, news, & reviews, subscribe to the newsletter (archives).

Miscellaneous