Equation 1 · Cities Are Organisms That Refuse to Die: Urban Evolution to 2100
What does this equation mean?
Read the formula alongside the article passage below. Each part has a deeper page with its role in the equation, the supporting passage and nearby citations.
This mathematical expression combines the displayed quantities; its precise role follows from the surrounding article text. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.
Read it piece by piece
Symbol Y
Y is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
How to interpret it
Read this expression with the definitions, units, and assumptions supplied by the article.
What the article says around this equation
In 2007, Bettencourt, Lobo, Helbing, Kühnert and West published a cross-sectional analysis of American metropolitan statistical areas that has since become the standard citation for the claim that cities obey scaling laws. Measured against city population, quantities tied to innovation and economic output scale superlinearly — new patents scaled with an exponent of 1.27, inventors 1.25, private research and development employment 1.34, GDP in a range of 1.15 to 1.26, total wages 1.12, even serious crime 1.16 — while quantities tied to physical infrastructure scale sublinearly: length of electrical cable 0.87, road surface 0.83, gasoline stations 0.77, gasoline sales 0.79 [ 1 ] . In the…
Read the full surrounding passage
In 2007, Bettencourt, Lobo, Helbing, Kühnert and West published a cross-sectional analysis of American metropolitan statistical areas that has since become the standard citation for the claim that cities obey scaling laws. Measured against city population, quantities tied to innovation and economic output scale superlinearly — new patents scaled with an exponent of 1.27, inventors 1.25, private research and development employment 1.34, GDP in a range of 1.15 to 1.26, total wages 1.12, even serious crime 1.16 — while quantities tied to physical infrastructure scale sublinearly: length of electrical cable 0.87, road surface 0.83, gasoline stations 0.77, gasoline sales 0.79 [ 1 ] . In the compact notation the paper made famous, a quantity Y relates to population N as
Sources cited in the surrounding passage
These citations give research context. Read each source to check which claims it supports.
Return to Cities Are Organisms That Refuse to Die: Urban Evolution to 2100