Price Controls set a price ceiling or floor for specified transactions. A nominal limit alone proves neither availability nor resulting purchasing power.
A ceiling prohibits prices above a limit; a floor prohibits prices below it. Do not reverse these meanings according to whether the measure aims to help buyers or sellers. [OpenStax — Price Ceilings and Price Floors]
In the basic competitive model, a ceiling above equilibrium or a floor below it does not constrain the price. The law still applies; market changes may make it bind. [OpenStax — Price Ceilings and Price Floors]
A binding ceiling below equilibrium creates excess quantity demanded; a floor above it creates excess quantity supplied. This is a result of the stated model, not a universal estimate for every regulated market. [OpenStax — Price Ceilings and Price Floors]
Our floor example: supply of 120 units and demand of 80 leave excess supply of 40. Selling all 120 requires another buyer or some other change; government purchases are not assumed. [OpenStax — Price Ceilings and Price Floors]
Mises’s milk example illustrates queues and rationing during shortages. Track who obtains the product and the time or other costs they sacrifice, not only the posted price. [Mises — Economic Policy: Interventionism]
For controlled rents, OpenStax describes reduced maintenance and units leaving the rental market. This possible response is not the same as buildings immediately disappearing physically. [OpenStax — Price Ceilings and Price Floors]
The 2019 study examines a 1994 rule change in San Francisco. It finds less displacement of incumbent tenants and reduced rental supply by affected landlords; do not automatically generalise to all controls. [Diamond, McQuade and Qian — Rent Control Expansion in San Francisco (2019)]
A protected tenant’s benefit can coexist with worse housing access for others. Assess groups, time horizons and what would have happened without the rule change separately. [Diamond, McQuade and Qian — Rent Control Expansion in San Francisco (2019)]
For the clearest picture, read this entry together with Interventionism, Opportunity Cost, Subjective Value Theory, Economic Calculation. The reverse links also lead from Interventionism.