Cross-elasticity of demand
The cross-elasticity of demand is the percent change in the quantity purchased of one good or service due to the percent change in price of another good or service.
This is similar to the price elasticity of demand except that two goods or services are compared in the cross-elasticity of demand.
An example of services having a cross-elasticity of demand are the services of abortion and childbirth. When the price increases for abortion, the demand for childbirth services increases.