ClaimsNassim Taleb

“In the lognormal case of Figure 1, 85% of all observations fall below the mean”

Taleb, co-author of the paper July 2020 On Single Point Forecasts for Fat-Tailed Variables (arXiv) archived copy

Factual Science and research methods

In the lognormal distribution used in the paper's Figure 1, 85% of observations fall below the mean.

Unresolvable The public record could not settle it.

Factual: Statements about the present or the past, checked against the record: did they hold up?

What would count as true or false

Identify the lognormal distribution in Figure 1 of the July 2020 paper by its stated parameters (for a lognormal with log-standard-deviation σ, the share below the mean is Φ(σ/2)). True: the share of observations below the mean, computed from the paper's stated parameters (or shown in its figure or data), is about 85%, within ±1 percentage point. Mostly true: within ±3 percentage points. Mostly false: the share is a clear majority but differs by more than 3 points (for example 70–80% or above 90%). False: the share is far from 85% or not a majority, or Figure 1 does not show a lognormal distribution.

Set before the research began.

Evidence (2)

  1. E1 Lognormal Distribution Calculator - Precise Calculators Precise Calculators · 4 October 2026

    “The share of values below the mean equals Φ(σ ÷ 2).”

  2. E2 Lognormal Distribution Calculator - Precise Calculators Precise Calculators · 4 October 2026

    “At σ = 1, almost seven in ten observations fall below the average”

Reasoning

E1 gives the general formula: the share of a lognormal's values below its mean is Φ(σ/2). E3 says that at σ = 1 almost seven in ten observations fall below the mean. Neither source identifies the paper's Figure 1 or states its parameters, and none of the evidence comes from the July 2020 paper itself. So the share below the mean for the distribution in that figure can't be computed, and the 85% claim can't be checked.

Cite this claim

Nassim Taleb, “In the lognormal distribution used in the paper's Figure 1, 85% of observations fall below the mean.” (said July 2020). Verdict: unresolvable. Reliability API, claim c_bc7cb5c1c852, method 0.1.0+28da144b, dataset release v1.1.2. https://epistacklabs.com/claims/c_bc7cb5c1c852

This claim is in dataset release v1.1.2, with the same verdict.

Reply to this claim

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  5. Mostly true Factual 2023
    “A sum of such bets becomes rapidly”

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All of them

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