Chinese reign era names were reused by rival courts, and most Ming and Qing emperors began theirs at New Year
Chinese emperors named their years by era names, and a date was written as the era plus a year count. Catalogues disagre...
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Riegel's race-time formula comes within about 2% of world records and predicts recreational marathons too fast
Riegel's formula scales a known race time to another distance using an exponent, usually 1.06. Tested against world reco...
Descriptive and algebraic chess notation, and the rules FIDE and PGN files disagree on
Old chess books write moves in descriptive notation, naming each square from the mover's side, while FIDE's Laws recogni...
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Hundreds of subject combinations can add up to the same PSLE Score
Singapore's PSLE Score adds four Achievement Levels into a total from 4 to 32, where lower is better, and MOE sorts thos...
Singapore's golf tees turn one handicap index into very different stroke counts
A Course Handicap rescales a golfer's Handicap Index by the Slope Rating of the tee being played. Across the 88 tees the...
Net run rate tables from the ICC add up only when overs are counted in balls
Net run rate is a cricket side's runs per over minus the runs per over scored against it, across every match with a resu...
One study's medium Cohen's d is compatible with effects from below small to large
Cohen's d, Hedges' g and Glass's Δ all divide a difference between two means by a standard deviation, and differ in whic...
Readability formulas fitted to the same readers still disagree by about a grade and a half
Flesch-Kincaid, SMOG and other readability formulas give one text different grade levels because each counts a different...
Generation charts disagree on a third of post-war birth years
Pew, McCrindle, the US Census Bureau and Indonesia's statistics office give different generation labels, or none, for 27...
Division codes from China's Ministry of Civil Affairs survive renames and change with a place's type
China's Ministry of Civil Affairs gives province-, prefecture- and county-level units six-digit codes, and all but one o...
Malaysia's open postcode list names 2,930 codes
MCMC's open postcode list names 2,930 Malaysian postcodes. How the first two digits mark the state, the one code outside...
Converting Japanese era years, and why Japanese law still names Heisei 72
Reiwa 8 is 2026: add 2018, and 1988, 1925, 1911 or 1867 for the earlier eras. The four days when the era changed and the...
Taiwan's 22 counties and cities, read from the household register
Taiwan's 22 counties and cities (台灣22縣市) on the household register for August 2026: population, area and density for...
Chinese measure words ranked by how often they are actually used
How often 个 really fills the measure-word slot in Chinese text, which two dozen classifiers (量词) cover nine tenths of...
Hong Kong's 18 districts by population, density and council seats
Hong Kong's 18 districts (18區) on the census department's mid-2025 figures: which are most crowded, how the regions sha...
HSK 3.0 word counts by level, and how far old HSK words carry over
The syllabus the new HSK is tested on lists 11,000 words: 300 for level 1 up to 5,400 by level 6, with levels 7 to 9 sha...
How many Indonesian words can you make from seven letters
A random rack of seven letters makes a median of at least 23 Indonesian words, but a word using all seven turns up for o...
How to count fan in Hong Kong mahjong, and why every table scores differently
In Hong Kong mahjong every table agrees that all chows is 1 fan and a full flush 7, but the rarer hands and the payout s...
How many Chinese characters cover 90% of what you read
About a thousand characters make up 90% of written Chinese, but in film subtitles it is 717, and half of what is said on...
The idioms that end a game of 成语接龙
In 成语接龙, the idiom chain game, some idioms leave the next player nothing to say. Here are the dead ends and two-move...
One Singapore quarter, two official growth rates, four times apart
In August 2020 the economy had shrunk 41.2% in the second quarter; in October the same quarter was a 13.2% contraction....
The annual Sharpe ratio hides an assumption about your returns
Annualising a monthly Sharpe ratio by multiplying by the square root of twelve is not a unit conversion. It is Andrew Lo...
A distress-zone Z-score does not mean a 70% chance of bankruptcy
The Altman Z-score's famous 70% is the share of firms that DID fail which had scored in the distress zone — a sensitivit...
Why Your Best Performers Get Worse
A thousand simulated pages whose true conversion rates never change. Selected on one period's numbers, the top tenth app...
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