Motivating factors are more complex and the sort of things we'll be talking about here something we call income elasticity.

The income elasticity of demand for electricity is estimated by Eletrobras at above unity.

The income elasticity of the value of statistical life has been estimated at 0.5 to 0.6.

The income elasticity of a necessity good is thus between zero and one.

It did not put forward any estimate of the income elasticity of demand.

In either case, public spending should increase by the income elasticity of demand.

The effect is similar to a change in income and depends upon the income elasticity of demand.

Patterns and changes in sectoral employment drive demand shifts through the income elasticity.

In other words, the income elasticity of demand of food is between 0 and 1.

Wagner was in effect suggesting that public sector services and products are 'normal', with high income elasticities of demand.