Relative or Absolute Poverty Lines: a New Approach

When measuring poverty over time analysts must choose the value of the income elasticity of the poverty line, which essentially determines whether an absolute or relative poverty line is being used. The choice of this parameter is ultimately a value judgement, but this paper suggests an approach which has some empirical basis. Borrowing from the life-style and deprivation approach to poverty, various dimensions of poverty and deprivation are identified and the income elasticity of these items is used as the income elasticity of the poverty line. Data from the 1987 and 1994 Irish Household Budget Surveys suggest an upper bound of 0.7 for this parameter. Poverty measures using a number of values of the income elasticity of the poverty line are presented and test statistics are presented to determine whether observed differences in poverty measures are statistically significant.