- noun the frequency of occurrence of something
- (written as Incidence)
This has wholly different meanings in epidemiology and economics. In epidemiology, 'incidence' is the number of new cases of a disease identified during a time period. It is usually expressed as the proportion of those who are susceptible or at risk at the beginning or middle of the period.
In economics, 'incidence' concerns who pays taxes and various other costs, that is, who bears the ultimate distribution of the burden after all effects arising from the elasticities of demand and supply have been allowed to work their way out. Unless the elasticities of demand and supply have very extreme low values, economists generally expect there to be what is known as shifting. Thus, it may appear self-evident that a tax, like a payroll tax to fund health insurance, or compulsory copayment, is paid by whoever gives up the cash, writes a cheque or pays by credit card. There is, however, a difference between the statutory, or formal, incidence of tax (the persons who initially pays) and the final or economic incidence. Thus, in the case of a general payroll tax, the immediate impact is to reduce the take-home pay of workers; this will cause the supply of labour to fall and generate a (partially) compensating rise in the wage rate (depending on the elasticity of supply) through which a part of the burden of the tax is paradoxically shifted on to the owners of capital. The prices of goods will also rise, with goods and services produced in labour-intensive industries rising more than elsewhere (depending on the relative elasticity of demand for them), thereby shifting some of the burden of the tax on to consumers of the more labour-intensive goods. In the economy as a whole, the capital-labour ratio will fall.
Similar sorts of effects will arise when one is analysing the impact of diseases on labour productivity, wages and movements in the labour market. It also turns out that the prevalence of a disease is a potentially important determinant of such impacts.
- noun the number of sports injuries incurred in a sample population, relative to the amount of time exposed to the risk