Filtered dossier

Hidden Numbers

Quantities that hide a rule you never agreed to.

  • 12 / 12
  • No visual on file
    Price Psychology Entry #0354

    The reason free shipping outperforms an equal discount

    Removing a five-pound delivery fee converts better than taking five pounds off the item. The two are arithmetically identical and psychologically separate.

    Adept
    The hidden part #0354

    A fee is a loss with no matching gain. Folding it into the price removes the loss without changing the total.

    Open file
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    Price Psychology Entry #0352

    The reason a decoy tier makes the middle look reasonable

    Three tiers on a pricing page: cheap, middle, expensive. The expensive one is not there to be chosen. It is there to make the middle one look like the sensible option.

    Adept
    The hidden part #0352

    Value is judged by comparison, not absolutely. The tier nobody buys is the one that decides what everyone else buys.

    Open file
  • No visual on file
    Market Signals Entry #0402

    The reason a degree signals more than it teaches

    Part of a qualification’s value comes from what finishing it proves about the person, rather than from what the person learned inside it.

    Adept
    The hidden part #0402

    A credential can be worth paying for even where the teaching is not, provided it is hard to obtain.

    Open file
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    Incentive Design Entry #0376

    Why paying for blood donations reduced supply

    Adding money to a voluntary act can reduce how often it is performed, because the payment replaces the reason people were doing it at all.

    Novice
    The hidden part #0376

    A payment does not only add a motive. It can delete the one that was already there.

    Open file
  • No visual on file
    Price Psychology Entry #0351

    Why nine at the end of a price still works

    Prices ending in nine still outsell round neighbours, and the reason is not that shoppers are fooled about the total but how the number is read.

    Novice
    The hidden part #0351

    A price is read left to right and encoded before it is finished, so the first digit does most of the work.

    Open file
  • No visual on file
    Statistical Illusions Entry #0441

    The reason per capita reverses many rankings

    Dividing by population removes size from a comparison. Since size drives most totals, the ranking that survives is often the opposite of the original.

    Adept
    The hidden part #0441

    A total measures magnitude and a rate measures intensity. Which one is published decides most of the ranking.

    Open file
  • No visual on file
    Statistical Illusions Entry #0440

    Why counting something changes what gets counted

    A measure requires a definition, and once the measure is consequential the definition becomes something to be managed rather than merely applied.

    Master
    The hidden part #0440

    A number is a definition applied to the world. Make the number consequential and the definition becomes the thing under negotiation.

    Open file
  • No visual on file
    Statistical Illusions Entry #0439

    The reason a forecast range matters more than its midpoint

    A single number implies a precision the forecast does not have. The width of the interval is the part that says how much the forecast actually knows.

    Adept
    The hidden part #0439

    Two forecasts with the same midpoint and different widths are different forecasts. Only one of those numbers usually survives.

    Open file
  • No visual on file
    Statistical Illusions Entry #0438

    Why the median rent tells you more than the average

    A mean is pulled by every extreme value in the set. A median is not, so for skewed quantities it describes the ordinary case far more closely.

    Novice
    The hidden part #0438

    A mean answers a question about the total. For a skewed quantity, only the median approximates the ordinary case.

    Open file
  • No visual on file
    Scarcity & Queues Entry #0467

    Why a raffle allocates differently than a price

    A lottery gives everyone the same chance and no way to express how much they need the thing. A price does the reverse, and each ignores what the other records.

    Adept
    The hidden part #0467

    Every allocation rule declares which claims count. A lottery says all equally; a price says according to capacity to pay.

    Open file
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    Scarcity & Queues Entry #0466

    The reason first come first served changes who arrives

    A queue does not distribute a good neutrally. It charges in time, so it selects the people for whom time is the cheapest thing to spend.

    Adept
    The hidden part #0466

    A queue charges in time. It allocates to those with the least valuable hours, not to those with the greatest need.

    Open file
  • No visual on file
    Scarcity & Queues Entry #0464

    The reason a return window changes the decision to keep

    A longer window looks like more protection for the buyer. It is also more time in which the item stops being a purchase and becomes a possession.

    Adept
    The hidden part #0464

    A return window is not only time to decide. It is time in which the item stops being a candidate and becomes yours.

    Open file