Use this sociology calculation to reproduce a named demographic, inequality, mobility, urban, or survey measure when the population, period, categories, and coding rules are explicit.

Destination population

Required number. Population at the destination.

Distance (km)

Required number in km. Distance separating the two places.

Origin population

Required number. Population at the origin.

The cited overview of Sociology supplies background for the terminology and domain context used by this tool.^[1]

Rank migration potential between two places with the gravity model product of populations over squared distance. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Gravity index

Returned number. Gravity potential; higher values predict larger interaction flows.

• Definitions, sampling error, missing data, historical context, geographic boundaries, weighting, and classification choices can materially change social indicators and their interpretation.
• Destination population must be at least 0.
• Distance must be at least 5e-324.
• Origin population must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Report the source population and uncertainty, inspect disaggregated data, and compare multiple accepted indicators rather than treating one summary statistic as a complete social explanation.

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  Fit the negative exponential of Clark's urban density model between two ring measurements.

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  Score urban primacy as the largest city's population over the combined next three cities.