|(1) average income was calculated for the poverty quintile, and the quintile above and below (in the case in which the poverty quintile was the first, see below);|
|(2) within each quintile it was assumed that mean income equalled the median; 17 this assumption locates within each quintile the percentile for mean income; and|
|(3) between each mean income, income was assumed to rise at a constant rate.|
For example, the rate of increase of income between mean income in quintile one (Pm1) and quintile two (Pm2) would be:
If Pm1 were at the fourteenth percentile, the income of the twentieth percentile would be P20 = (1 + r)6 (Pm1). If the poverty line lies within the first quintile, the value of r between the first and second quintile means it is used to calculate downwards to the first percentile. On the basis of this method, the percentile for the absolute poverty line for each country can be found by generating the income for each percentile until Pi = US$ 365 is reached (Table 7A.1).