The difference between this indicator and the initial poverty rate is the distribution effect Both effects can also be calculated by exchanging the initial and end periods. Both obstacles can be overcome by averaging the calculated effects using each of the two base years respectively (Kakwani.i997>, which is the procedure used to perform the calculations in this chapter. Journal of Development Economics, vol. Amsterdam, Elsevier, 1992. For this analysis, and in the absence of longitudinal surveys that would serve to identify changes in the income sources of the same households, the variations between 2012 and 2017 are studied for the same proportion of households (those whose per capita income at the start of the period was below the poverty line). Thus, if poor households represented 20% of the total in 2012, for 2017 the poorest 20% of households by income are selected, regardless of whether the households in that range are living in poverty or not.