A High R² Does Not Mean the Model Is Right
Anscombe printed one regression summary for four data sets in 1973 and said the features that matter are "invisible if w...
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Standard Deviation vs Standard Error: Two Numbers, Two Questions
Mean ± 4.36 and mean ± 0.97 are not two ways of saying the same thing. Altman and Bland assigned each to a different que...
What a 95% Confidence Interval Actually Means
Nearly everyone reads a confidence interval as "there is a 95% probability the true value is in here" — including 59% of...
UUID v4 vs v7 in 2026: v1 Was Never the Sortable One
RFC 9562 replaced RFC 4122 in May 2024, and the advice most codebases still follow did not update with it. UUID v1 is ti...
Decoding a JWT Is Not Verifying It
A decoder shows you the claims; it does not tell you whether to believe them. RFC 7519 §7.2 lists ten validation steps a...
Encoding Is Not Encryption: Base64, Percent-Encoding and the Confusion That Leaks Data
The RFC that defines Base64 says in its own Security Considerations that base encoding "visually hides" a password but "...
Which Hash for What: MD5, SHA-256, and the Password Mistake
"MD5 is broken, so hash your passwords with SHA-256 instead" gets both halves wrong, in opposite directions. What broke...
How a Luopan Actually Works: the Chinese Compass and Its 24 Mountains
An honestly-framed look at the Chinese geomantic compass as an instrument: the needle housing, the rotating plate, and t...
Feng Shui Kua Numbers and the Eight Mansions, Explained: One Formula, Eight Trigrams, Three New Years
An honestly-framed look at how Eight Mansions (八宅) is actually constructed: the Later Heaven trigram grid it runs on,...
P/E, PEG and DCF: Three Ways to Tell If a Stock Is Actually Cheap
A low share price is not a cheap stock. Here is what the P/E ratio, the PEG ratio, discounted cash flow and the dividend...
The Chinese Zodiac Beyond Horoscopes: 12 Animals, 5 Elements, and How Compatibility Really Works
An honestly-framed look at how the Chinese zodiac is actually built: the twelve animals and the ancient Earthly Branches...
Attachment Styles: What Anxious, Avoidant and Secure Actually Mean
Anxious, avoidant, secure — the labels are everywhere, but unlike most personality quizzes, adult attachment has real re...
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