45 lines
1.3 KiB
Markdown
45 lines
1.3 KiB
Markdown
---
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id: 2026-01-25T22:59:00-0500
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title: 2026-01-25 22:59:??
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tags:
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- topic/estimating
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daily: "[[2026-01-25]]"
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---
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# 2026-01-25 22:59:??
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## _Judgmental Decomposition_
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[[macgregor_1994_judgmental-decomposition]]
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I really hate this study.
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I may be out of my league,
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but it seems wrong to draw conclusions about decomposition as a method
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when the work was done by the researchers,
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especially when some of their decompositions really suck.
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> ##### Circumference of 50¢ coin
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>
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> * Diameter in inches of a 50¢ coin
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> * Number of pieces of string the length of the diameter needed to wrap around circumference
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That's not a decomposition.
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If you don't remember $\pi$
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that's a harder problem than it was before.
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> ##### Bushels of wheat
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>
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> * Population of the world
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> * Number of bushels of wheat consumed per person per year
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> * Proportion of wheat wasted per year
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I might have included _how much a bushel is_,[^1]
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there's an order of magnitude right there.
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[^1]: $1~\text{US bushel} \equiv 9\frac{3571}{11550}~\text{US Gallons} \approx 9.3~\text{US Gallons}$
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The study suggests decomposition has no effect on estimate _confidence_
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---which I'm tempted to believe because its funny
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and it tracks with my anecdotal experience---
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but I wonder if subjects using their own decompositions would present similarly.
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