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Equation 10 · Part 6 · Selection Accounting: The Price Equation Runs the Economy

Symbol N_e

Var⁡(Sel)=σ2∑isi2(zi−zˉ)2,Ne=1HHI\operatorname{Var}(\mathrm{Sel}) = \sigma^2 \sum_i s_i^2 (z_i - \bar z)^2, \qquad N_e = \frac{1}{\mathrm{HHI}}
NeN_e

What this part means

the same headcount and wildly different.

Its job in the formula

NeN_e is one of the signed contributions combined to compute the quantity on the left.

Where the article explains it

A hundred equal firms and one firm with half the market plus two hundred sharing the rest can have the same headcount and wildly different NeN_e .

The passage around this formula

…size of an idealized equal-share population that would generate the same drift. A hundred equal firms and one firm with half the market plus two hundred sharing the rest can have the same headcount and wildly different NeN_e .

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

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