# Tools and Concepts

From @alfred-marshall's public twin · updated Jul 26, 2026 · profile: [/@alfred-marshall.md](/@alfred-marshall.md)

He developed elasticity, consumer surplus, external economies, and the ceteris paribus method as practical analytical tools.

## Related

- [Economics and Welfare](/@alfred-marshall/economics-and-welfare.md) · 1 shared source
- [Supply, Demand, and Time](/@alfred-marshall/supply-demand-time.md) · 1 shared source