https://twitter.com/davidmanheim/status/963071765995032576
https://archive.is/njT4P
A very good economics journal--famously an outlet for rigorous, outside the box thinking--is publishing a special issue on hidden meanings in the work of two of the world's greatest thinkers.

Another sign the new Straussian age is upon us: Bayesians update accordingly!

"Recently, long-past-due theoretical results have begun to emerge. These results, and those that will follow in their wake, will begin to shed light on the properties of large, adaptive, distributed learning architectures, and stand to revolutionize how computer science and neuroscience understand these systems."

This paper provides evidence of the long-run effects of a permanent increase in agricultural productivity on conflict. We construct a newly digitized and geo-referenced dataset of battles in Europe, the Near East and North Africa covering the period between 1400 and 1900 CE. For variation in permanent improvements in agricultural productivity, we exploit the introduction of potatoes from the Americas to the Old World after the Columbian Exchange. We find that the introduction of potatoes permanently reduced conflict for roughly two centuries. The results are driven by a reduction in civil conflicts

http://marginalrevolution.com/marginalrevolution/2017/12/monday-assorted-links-135.html#comment-159746885
#4 An obvious counterfactual is of course the potato blight (1844 and beyond) in Europe. Here’s the Wikipedia page ‘revolutions of 1848’ https://en.wikipedia.org/wiki/Revolutions_of_1848

Margulis went on to theorize that symbiotic relationships between organisms are the dominant driving force of evolution. There certainly are important examples of this: as far as I know, every complex organism that digests cellulose manages it thru a symbiosis with various prokaryotes. Many organisms with a restricted diet have symbiotic bacteria that provide essential nutrients – aphids, for example. Tall fescue, a popular turf grass on golf courses, carries an endosymbiotic fungus. And so on, and on on.

She went on to oppose neodarwinism, particularly rejecting inter-organismal competition (and population genetics itself). From Wiki: [ She also believed that proponents of the standard theory “wallow in their zoological, capitalistic, competitive, cost-benefit interpretation of Darwin – having mistaken him… Neo-Darwinism, which insists on [the slow accrual of mutations by gene-level natural selection], is in a complete funk.”[8] ‘

...

You might think that Lynn Margulis is an example of someone that could think outside the box because she’d never even been able to find it in the first place – but that’s more true of autistic types [like Dirac or Turing], which I doubt she was in any way. I’d say that some traditional prejudices [dislike of capitalism and individual competition], combined with the sort of general looniness that leaves one open to unconventional ideas, drove her in a direction that bore fruit, more or less by coincidence. A successful creative scientist does not have to be right about everything, or indeed about much of anything: they need to contribute at least one new, true, and interesting thing.

https://westhunt.wordpress.com/2017/11/25/lynn-margulis/#comment-98174
“A successful creative scientist does not have to be right about everything, or indeed about much of anything: they need to contribute at least one new, true, and interesting thing.” Yes – it’s like old bands. As long as they have just one song in heavy rotation on the classic rock stations, they can tour endlessly – it doesn’t matter that they have only one or even no original members performing. A scientific example of this phenomena is Kary Mullins. He’ll always have PCR, even if a glowing raccoon did greet him with the words, “Good evening, Doctor.”

Nobel Savage: https://www.lrb.co.uk/v21/n13/steven-shapin/nobel-savage
Dancing Naked in the Mind Field by Kary Mullis

jet fuel can't melt steel beams: https://westhunt.wordpress.com/2017/11/25/lynn-margulis/#comment-98201
You have to understand a subject extremely well to make arguments why something couldn’t have happened. The easiest cases involve some purported explanation violating a conservation law of physics: that wasn’t the case here.

Do I think you’re a hotshot, deeply knowledgeable about structural engineering, properties of materials, using computer models, etc? A priori, pretty unlikely. What are the odds that you know as much simple mechanics as I do? a priori, still pretty unlikely. Most likely, you’re talking through your hat.

Next, the conspiracy itself is unlikely: quite a few people would be involved – unlikely that none of them would talk. It’s not that easy to find people that would go along with such a thing, believe it or not. The Communists were pretty good at conspiracy, but people defected, people talked: not just Whittaker Chambers, not just Igor Gouzenko.

https://www.wsj.com/articles/arkema-report-said-chemical-could-put-one-million-at-risk-1504215571
A chemical stored at a Houston plant that caught fire early Thursday morning presents an airborne danger to more than 1 million people if released in a worst-case scenario, according to a company risk management plan filed to the federal government.
http://www.latimes.com/nation/la-na-harvey-engineering-20170828-story.html
http://www.newyorker.com/news/news-desk/why-does-america-need-the-cajun-navy
https://twitter.com/_TamaraWinter/status/903613511082921984
I think this (generally nice) story about the Cajun Navy + groups like it misunderstands civil society in a big way.
How quickly can we adapt to change? An assessment of hurricane damage mitigation efforts using forecast uncertainty: https://www.economics.ox.ac.uk/materials/papers/15156/831-martinez.pdf

some discussion by Cochran here: https://pinboard.in/u:nhaliday/b:d76c7ed6b0cb

Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy
https://twitter.com/HoustonEuler/status/887479542360702977
My embedded opinion is that Cathy O'Neil frequently writes foolish things
She's a former mathematician/finance quant who dresses up a lot of progressive dogma with phony skepticism

http://www.vdare.com/tag/minority-mortgage-meltdown
http://www.slate.com/articles/business/moneybox/2008/10/subprime_suspects.html
http://voxeu.org/article/minority-mortgage-market-and-crisis

Causes of the Financial Crisis: https://spottedtoad.wordpress.com/2016/01/17/causes-of-the-financial-crisis/
Look, Wall Street was definitely a bad actor from 2000-2008. But the idea that they were solely responsible for the crisis has got to go. There were four main factors, in descending order:

a) A huge global savings glut that meant there were vast amounts of cash people were eager to lend out, combined with…

b) Enormous pressures to make use of all that money to increase lending and reduce standards for lower-income and minority households.

This book has some of the story, mostly focusing on the expansion and growing political power of Freddie and Fannie in the 1990s, but it really wasn’t any secret that reducing credit-worthiness (sorry, barriers to homeownership) was an explicit goal of the Clinton and Bush administrations and affiliated banks. Bush gave a long speech on these goals in mid-2002. Countrywide, led by Angelo Mozilo, pledged $600 billion in loans to low-income and minority homeowners in early 2003. Then, the Bush administration was bragging in late 2004 about the commitments they had elicited from lenders to expand low-income and minority lending by over $1 Trillion. Then, a few months later, in 2005, Countrywide, with a former HUD secretary on its board, released a press release bragging that they were going to increase their book of lending to minority and low-income households to $1 Trillion. Looking back on the crisis, liberal sociologists find, unsurprisingly, that subprime lending and the subsequent foreclosures were concentrated in minority households.
c) The efforts to extend massive amounts of credit to non-creditworthy families were abetted by fraud and irresponsible borrowing by those same households. See, for example, Atif Mian’s papers on widespread fraud in mortgage applications.
d) Bad actions by Wall Street (Inside Job is probably a good version of this.)

The idea that only d matters is just nuts.

lol "epigenetics" makes an appearance ofc

https://www.theatlantic.com/science/archive/2017/06/the-moral-question-that-stanfords-bioengineering-students-get/531876/

For now, that’s prohibitively expensive, but it won’t always be that way. In 2003, it cost 4 dollars to press one of the keys on Endy’s hypothetical synthesizer. This month, it costs just two cents—a 200-fold decrease in price in just 14 years. In the same time frame, the cost of tuition at Stanford has doubled, and is now around $50,000. Given all of that, the first question that Stanford’s budding bioengineers get is this:

At what point will the cost of printing DNA to create a human equal the cost of teaching a student in Stanford?
And the answer is: 19 years from today.

But the follow-up question is a little more complicated:

If you and your future partner are planning to have kids, would you start saving money for college tuition, or for printing the genome of your offspring?
The question tends to split students down the line, says Endy. About 60 percent say that printing a genome is wrong, and flies against what it means to be a parent. They prize the special nature of education and would opt to save for the tuition. But around 40 percent of the class will say that the value of education may change in the future, and if genetic technology becomes mature, and allows them to secure advantages for them and their lineage, they might as well do that.

https://www.nytimes.com/2016/05/14/science/synthetic-human-genome.html
http://www.nature.com/news/plan-to-synthesize-human-genome-triggers-mixed-response-1.20028

https://ipscell.com/2017/06/crispr-human-genetic-modification-a-needed-course-correction/

not much of a difference by gender (seems female->more supportive in northern countries, less supportive in southern countries), biggest thing is urbanity+educational attainment

https://twitter.com/whyvert/status/899850410935975940
https://archive.is/nUJp2
Vote share for WEuro populist parties higher in regions: rural, ⇈foreigners, ⇈unemployment, AND ⇈education except in cities (surprising)
the urban educated hate the nationalist parties but the nonurban educated are prone to support them. Not all educated are alike

The success of radical right-wing parties in Western European regions – new challenging findings: http://www.tandfonline.com/doi/abs/10.1080/14782804.2016.1198691

Can Television Reduce Xenophobia? The Case of East Germany: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2932276
To examine this question, we exploit the fact that individuals in some areas of East Germany – due to their geographic location – could not receive West German television until 1989. We conjecture that individuals who received West German television were exposed more frequently to foreigners and thus have developed less xenophobia than people who were not exposed to those programs. Our results show that regions that could receive West German television were less likely to vote for right-wing parties during the national elections from 1998 to 2013. Only recently, the same regions were also more likely to vote for left-wing parties. Moreover, while counties that hosted more foreigners in 1989 were also more likely to vote for right-wing parties in most elections, we find counties that recently hosted more foreign visitors showed less xenophobia, which is in line with intergroup contact theory.

With an Open Mind: Openness to Experience Moderates the Effect of Interethnic Encounters on Support for Immigration: https://academic.oup.com/esr/article-abstract/33/5/721/4102111/With-an-Open-Mind-Openness-to-Experience-Moderates

Refugees Unwelcome? Changes in the Public Acceptance of Immigrants and Refugees in Germany in the Course of Europe’s ‘Immigration Crisis’: https://academic.oup.com/esr/article-abstract/doi/10.1093/esr/jcx071/4557564/Refugees-Unwelcome-Changes-in-the-Public
Derived from discussions making up the German immigration discourse during this time, we expect reduced acceptance especially of those immigrants who were explicitly connected to the salient events, like Muslims and the offenders of NYE. Most strikingly, we find that refugees were generally highly accepted and even more so in the second wave, whereas the acceptance of immigrants from Arab or African countries further decreased. Moreover, _female respondents’ initial preference for male immigrants_ disappeared. Contrary to our expectations, we find no changes in the acceptance of Muslims.

http://www.pewforum.org/2011/01/27/future-of-the-global-muslim-population-regional-europe/
http://www.pewforum.org/2011/01/27/the-future-of-the-global-muslim-population/#the-americas

Europe’s Growing Muslim Population: http://www.pewforum.org/2017/11/29/europes-growing-muslim-population/

https://www.gnxp.com/WordPress/2017/11/30/crescent-over-the-north-sea/
Pew has a nice new report up, Europe’s Growing Muslim Population. Though it is important to read the whole thing, including the methods.

I laugh when people take projections of the year 2100 seriously. That’s because we don’t have a good sense of what might occur over 70+ years (read social and demographic projections from the 1940s and you’ll understand what I mean). Thirty years though is different. In the year 2050 children born today, such as my youngest son, will be entering the peak of their powers.

[cf.: http://blogs.discovermagazine.com/gnxp/2012/12/population-projects-50-years-into-the-future-fantasy/]

...

The problem with this is that there is a wide range of religious commitment and identification across Europe’s Muslim communities. On the whole, they are more religiously observant than non-Muslims in their nations of residence, but, for example, British Muslims are consistently more religious than French Muslims on surveys (or express views constant with greater religious conservatism).

People in Western countries are violent (yes) 29 52 34
lmao that's just ridiculous from the UK

https://www.gnxp.com/WordPress/2006/03/03/poll-of-british-muslims/
In short, read the poll closely, this isn’t an black & white community. It seems clear that some people simultaneously support Western society on principle while leaning toward separatism, while a subset, perhaps as large as 10%, are violently and radically hostile to the surrounding society.

Hey! The organization that publishes all those Psychological Science-style papers has scheduled their featured presentations for their next meeting.

Included are:
– That person who slaps the label “terrorists” on people who have the nerve to question their statistical errors.
– One of the people who claimed that women were 20 percentage points were likely to vote for Barack Obama, during a certain time of the month.
– One of the people who claimed that women are three times as likely to wear red, during a certain time of the month.
– The editor of the notorious PPNAS papers on himmicanes, air rage, and ages ending in 9.
– One of the people who claimed, “That a person can, by assuming two simple 1-min poses, embody power and instantly become more powerful has real-world, actionable implications.”
– Yet another researcher who responded to a failed replication without even acknowledging the possibility that their original claims might have been in error.
– The person who claimed, “Barring intentional fraud, every finding is an accurate description of the sample on which it was run.”

The whole thing looks like a power play. The cargo-cult social psychologists have the power, and they’re going to use it. They’ll show everyone who’s boss. Nobody’s gonna use concerns such as failed replications, lack of face validity, and questionable research practices to push them around!

...

It’s a guild, man, nuthin but an ivy-covered Chamber of Commerce. Which is fine—restraint of trade is as American as baseball, hot dogs, apple pie, and Chevrolet.

The only trouble is that I’m guessing that the Association for Psychological Science has thousands of members who have no interest in protecting the interests of this particular club. I said it before and I’ll say it again: Psychology is not just a club of academics, and “psychological science” is not just the name of their treehouse.

Scientists are furious after a famous psychologist accused her peers of 'methodological terrorism': http://www.businessinsider.com/susan-fiske-methodological-terrorism-2016-9

When the Revolution Came for Amy Cuddy: https://www.nytimes.com/2017/10/18/magazine/when-the-revolution-came-for-amy-cuddy.html
As a young social psychologist, she played by the rules and won big: an influential study, a viral TED talk, a prestigious job at Harvard. Then, suddenly, the rules changed.

https://twitter.com/StuartJRitchie/status/920934644840849408
Silly me! I thought the rule "don't seek massive publicity for extremely flimsy results" had been around forever...

https://twitter.com/aleksjoksic/status/921507320978427904
Feeling victimized by criticism & the want to keep it quiet is related to a certain sex difference in doing science/intellectual discourse..
One mode is more masculine,the other is more feminine.@Steve_Sailer has great excerpts from Alastair Roberts on this http://www.unz.com/isteve/intellectual-discourse-taking/

controlling for demographics: http://www.pleeps.org/2016/06/23/the-mystery-of-millennial-politics/
https://twitter.com/epkaufm/status/903376370759196672
White millennials in US relatively similar to older whites in both partisanship & conservatism, shows Deborah Schildkraut at #APSA2017
https://twitter.com/wccubbison/status/903699883332427777
https://archive.is/WHpvc
Incredibly important paper from #APSA2017 by @debbiejsr & Satia Marotta on racial views of white millennials
cf: https://pinboard.in/u:nhaliday/b:8bdede501f24
https://twitter.com/SeanMcElwee/status/905104283036774400
People mistakenly believe that younger people have always been more liberal. In reality, the current age divide is larger than ever.

The future belongs to the Left: http://www.edwest.co.uk/spectator-blogs/the-future-belongs-to-the-left/
Labour is now the party of the middle class: http://www.edwest.co.uk/spectator-blogs/labour-is-now-the-party-of-the-middle-class/

The Zero-Sum Society: https://spottedtoad.wordpress.com/2017/06/12/the-zero-sum-society/
Record house prices are stopping couples having 160,000 children because they cannot afford bigger homes or are stuck in rental flats: http://www.dailymail.co.uk/news/article-4699862/House-prices-stopping-couples-having-160-000-children.html
https://static1.squarespace.com/static/56eddde762cd9413e151ac92/t/5968e14e86e6c08c90fda56c/1500045650060/Housing+and+fertility.pdf
Conservatism has no future unless it tackles housing: https://inews.co.uk/opinion/conservatism-no-future-unless-tackles-housing/
https://twitter.com/Birdyword/status/915676030110715904
https://archive.is/ezoDy
Wealth is unevenly distributed generally, but much less so in property than financial wealth - far bigger constituency for protecting it (Bristol Uni 2015)
This is why the 'house prices should fall' line is a dead end. Ex-pensions it's most of all the wealth majority of people have.

US at min wage: https://www.citylab.com/equity/2017/06/rent-is-affordable-to-low-wage-workers-in-exactly-12-us-counties/529782/

How Britain voted at the 2017 general election: https://yougov.co.uk/news/2017/06/13/how-britain-voted-2017-general-election/
In electoral terms, age seems to be the new dividing line in British politics. The starkest way to show this is to note that, amongst first time voters (those aged 18 and 19), Labour was forty seven percentage points ahead. Amongst those aged over 70, the Conservatives had a lead of fifty percentage points.
https://twitter.com/Peston/status/902990464697208835
This has got to embarrass most sensible Tory MPs
(poll numbers for specific issues)
https://twitter.com/tomhfh/status/917376537867051009
https://archive.is/IHhSz
John Curtice giving us @DUConservatives a slightly painful talk 😬
...
John Curtice is explaining that Labour’s economic policies did almost nothing to galvanise the young. It was their social liberalism.
Older voters more likely to care about rent control or redistribution than young.
Tuition fees are a misdiagnosis.
It’s SOCIAL LIBERALISM.
“In many ways the cues and mood music are more important than the policy.”
“The prominence of social issues have never been as big a dimension as they played in 2017.
Neither had the disparity in age.”

Easy Question: What growth rate advantage (additional GDP growth rate per annum) would savage, unfettered markets need to generate to justify these occasional disasters?

Answer: an additional 0.1 percent annual GDP growth would be more than enough. That is, an unregulated economy whose growth rate was 0.1 percent higher would, even after paying for each 20 year crisis, be richer than the heavily regulated comparator which avoided the crises but had a lower growth rate.

Hard Question: would additional regulation decrease economic growth rates by that amount or more?

Unless you think you can evaluate the relative GDP growth effects of two different policy regimes with accuracy of better than 0.1 percent, then the intellectually honest answer to the policy question is: I don't know. No shouting, no shaking your fist, no lecturing other people, no writing op eds, just I don't know. Correct the things that are obviously stupid, but don't overstate your confidence level about additional policy changes.

(Note I'm aware that distributional issues are also important. In the most recent era gains went mostly to a small number of top earners whereas the cost of the bailout will be spread over the whole tax base.)

http://voxeu.org/article/endogenous-growth-and-lack-recovery-global-crisis
Wall St. lending to Main St. even as many decry Dodd-Frank: https://apnews.com/0e4ee980a46549908733afb2f6824def/wall-st-lending-main-st-even-many-decry-dodd-frank

This paper studies how cultural norms shaped by negative historical shocks can explain conflicts in the long-run. Exploiting a unique dataset constructed from historical archives, we test whether the Irish Famine (1845-1850), one of the most lethal starvation in history, changed political attitudes and contributed to the Irish Revolution (1913-1921). First, we investigate the determinants of joining the rebellion movement on the basis of the 1911 Irish Census and the official lists of rebels. We find that rebels are more likely to be male, young, catholic and literate. Second, we explore whether the famine played a role in the probability of joining rebellion activities. Controlling for the level of economic development and other potential concurring factors, we provide evidence of the role of the great Irish famine as an exceptional legacy of rebellion during the movement of independence.

Activated History - The Case of the Turkish Sieges of Vienna: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3023816
We study whether long-gone but activated history can shape social attitudes and behavior even after centuries. We exploit the case of the sieges of Vienna in 1529 and 1683, when Turkish troops pillaged individual municipalities across East Austria. In 2005, Austrian right-wing populists started to campaign against Turks and Muslims and explicitly referred to the Turkish sieges. We show that right-wing voting increased in once pillaged municipalities compared to non-pillaged municipalities after the campaigns were launched, but not before. The effects are substantial: Around one out of ten votes for the far-right in a once pillaged municipality is caused by salient history. We conclude that campaigns can act as tipping points and catalyze history in a nonlinear fashion.

is this plausible?

the Black Death -> pastoralism -> female employment -> later marriage

From The Conversation: No, the Black Death did not create more jobs for women: https://ehsthelongrun.net/2017/02/09/from-the-conversation-no-the-black-death-did-not-create-more-jobs-for-women/

Two scientists with the Harvard–Smithsonian Center for Astrophysics stated that when, and even whether, the two galaxies collide will depend on Andromeda's transverse velocity.[3] Based on current calculations they predict a 50% chance that in a merged galaxy, the Solar System will be swept out three times farther from the galactic core than its current distance.[3] They also predict a 12% chance that the Solar System will be ejected from the new galaxy sometime during the collision.[9][10] Such an event would have no adverse effect on the system and the chances of any sort of disturbance to the Sun or planets themselves may be remote.[9][10]

Excluding planetary engineering, by the time the two galaxies collide the surface of the Earth will have already become far too hot for liquid water to exist, ending all terrestrial life; that is currently estimated to occur in about 3.75 billion years due to gradually increasing luminosity of the Sun (it will have risen by 35–40% above the current luminosity).[11][12]

Genetics and Society - Greg Cochran
playlist: https://www.youtube.com/playlist?list=PLR-XA68JQHV_tKVDPod50qVbh9TU0NLCL

some discussion by Pseudoerasmus on Galor and w/ economist in comments

https://westhunt.wordpress.com/2014/04/23/conferences/

interesting take from Garett Jones (very pro-capital): https://twitter.com/GarettJones/status/893550933065388032
https://archive.is/vHyMR
http://www.felixsalmon.com/2008/01/predatory-borrowers/

Central limit theorem and securitization: how to build a CDO: http://infoproc.blogspot.com/2008/11/central-limit-theorem-and_16.html

Merton on the financial crisis: http://infoproc.blogspot.com/2009/04/merton-on-financial-crisis.html

http://infoproc.blogspot.com/search/label/credit%20crisis

The Meridian: MBS, CDO's and CDS's In Layman's Terms......: http://themeridian.blogspot.com/2008/09/mbs-cdos-and-cdss-in-laymans-terms.html

The strain of bacteria that caused the Great Plague of London in 1665 has been identified for the first time. Scientists recovered DNA of Yersinia pestis—known to have been responsible for the Black Death in the 14th century—from skeletons discovered last year during the construction of the new Crossrail underground rail link beneath London.

Bush informed of 9/11 attack - Dramatization: https://www.youtube.com/watch?v=cVFDptvbFT8
curb your 9/11

It takes advantage of each year having a certain day of the week, called the doomsday, upon which certain easy-to-remember dates fall; for example, 4/4, 6/6, 8/8, 10/10, 12/12, and the last day of February all occur on the same day of the week in any year. Applying the Doomsday algorithm involves three steps:
1. Determination of the anchor day for the century.
2. Calculation of the doomsday for the year from the anchor day.
3. Selection of the closest date out of those that always fall on the doomsday, e.g., 4/4 and 6/6, and count of the number of days (modulo 7) between that date and the date in question to arrive at the day of the week.

This technique applies to both the Gregorian calendar A.D. and the Julian calendar, although their doomsdays are usually different days of the week.

Easter date: https://en.wikipedia.org/wiki/Computus
https://www.tondering.dk/claus/cal/easter.php
*When is Easter? (Short answer)*
Easter Sunday is the first Sunday after the first full moon on or after the vernal equinox.

*When is Easter? (Long answer)*
The calculation of Easter is complicated because it is linked to (an inaccurate version of) the Hebrew calendar.

...

It was therefore decided to make Easter Sunday the first Sunday after the first full moon after vernal equinox. Or more precisely: Easter Sunday is the first Sunday after the “official” full moon on or after the “official” vernal equinox.

The official vernal equinox is always 21 March.

The official full moon may differ from the real full moon by one or two days.

...

The full moon that precedes Easter is called the Paschal full moon. Two concepts play an important role when calculating the Paschal full moon: The Golden Number and the Epact. They are described in the following sections.

...

*What is the Golden Number?*
Each year is associated with a Golden Number.

Considering that the relationship between the moon’s phases and the days of the year repeats itself every 19 years (as described in the section about astronomy), it is natural to associate a number between 1 and 19 with each year. This number is the so-called Golden Number. It is calculated thus:

GoldenNumber=(year mod 19) + 1

[link:
However, 19 tropical years is 234.997 synodic months, which is very close to an integer. So every 19 years the phases of the moon fall on the same dates (if it were not for the skewness introduced by leap years). 19 years is called a Metonic cycle (after Meton, an astronomer from Athens in the 5th century BC).

So, to summarise: There are three important numbers to note:

A tropical year is 365.24219 days.
A synodic month is 29.53059 days.
19 tropical years is close to an integral number of synodic months.]

In years which have the same Golden Number, the new moon will fall on (approximately) the same date. The Golden Number is sufficient to calculate the Paschal full moon in the Julian calendar.

...

Under the Gregorian calendar, things became much more complicated. One of the changes made in the Gregorian calendar reform was a modification of the way Easter was calculated. There were two reasons for this. First, the 19 year cycle of the phases of moon (the Metonic cycle) was known not to be perfect. Secondly, the Metonic cycle fitted the Gregorian calendar year worse than it fitted the Julian calendar year.

It was therefore decided to base Easter calculations on the so-called Epact.

*What is the Epact?*
Each year is associated with an Epact.

The Epact is a measure of the age of the moon (i.e. the number of days that have passed since an “official” new moon) on a particular date.

...

In the Julian calendar, the Epact is the age of the moon on 22 March.

In the Gregorian calendar, the Epact is the age of the moon at the start of the year.

The Epact is linked to the Golden Number in the following manner:

Under the Julian calendar, 19 years were assumed to be exactly an integral number of synodic months, and the following relationship exists between the Golden Number and the Epact:

Epact=(11 × (GoldenNumber – 1)) mod 30

...

In the Gregorian calendar reform, some modifications were made to the simple relationship between the Golden Number and the Epact.

In the Gregorian calendar the Epact should be calculated thus: [long algorithm]

...

Suppose you know the Easter date of the current year, can you easily find the Easter date in the next year? No, but you can make a qualified guess.

If Easter Sunday in the current year falls on day X and the next year is not a leap year, Easter Sunday of next year will fall on one of the following days: X–15, X–8, X+13 (rare), or X+20.

...

If you combine this knowledge with the fact that Easter Sunday never falls before 22 March and never falls after 25 April, you can narrow the possibilities down to two or three dates.

the plague and economic modernization