petrogradphilos

5 ms·

1.
by petrogradphilos 6y ago
I like what you've written here. If you write stuff elsewhere, please put a pointer in your HN profile. Judging by your influences as an architect, I think you would enjoy these books: - Ronald Ross, Principles of the Business Rule Ap
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by petrogradphilos 6y ago
> You will never understand every detail of the implementation of every level on that stack; but you can understand all of them to some level of abstraction, and any specific layer to essentially any depth necessary for any purpose. As D
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by petrogradphilos 7y ago
> (1 - 2e-6)^(3e6) ≈ 0.002 Using the binomial directly is a good way to get the probability of 0 heads. Note, though, that the U.S. population is in the neighborhood of 300 million, not 3 million (as you seem to have used). (1 - 2⋅10⁻⁶)^
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by petrogradphilos 7y ago
> Since 0 is about 25 standard deviations from the mean, the probability of seeing 0 heads is on the order of 10⁻¹³⁸. Note: the above figure comes from the normal approximation to the binomial, which loses accuracy towards the tails. The
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by petrogradphilos 7y ago
This is like having a weighted coin that comes up heads with probability 2⋅10⁻⁶, flipping it 311 million times, and seeing 0 heads. That's astronomically unlikely. To see this, observe that the number of heads follows a binomial distri
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by petrogradphilos 7y ago
You could also replace % with 10⁻² and use scientific notation: 0.72% ⋅ 0.03% = 0.72 ⋅ 10⁻² ⋅ 0.03 ⋅ 10⁻² = 7.2 ⋅ 10⁻³ ⋅ 3 ⋅ 10⁻⁴ = 7.2 ⋅ 3 ⋅ 10⁻³ ⋅ 10⁻⁴ = 21.6 ⋅ 10⁻⁷ = 2.16 ⋅ 10⁻⁶ ≈ 2 in 1 million
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by petrogradphilos 7y ago
Never use a macro to do an inline function’s job.
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by petrogradphilos 7y ago
It’s correct to regard trees, but not people, as products of their environment. Trees don’t make choices. People do.
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by petrogradphilos 7y ago
> 1 Introduction > The increased availability of data linking students to teachers has made it possible to estimate the contribution teachers make to student achievement. There was some data available before (or the sentence would not