28
Stata Technical Bulletin
STB-48
Cum. Dist. of eqinc_m/_N
Cum. Pop. Prop.
Cum. Dist. of mchpay/_N
Population Share, p_i
Lorenz and Concentration Curves
Figure 3. Lorenz and concentration curves for child benefits.
Let us finally show how TIP curves can be constructed. Suppose we wish to make poverty comparisons among two population
subgroups, households who own their house (solid lines below) and households who rent their house (dashed lines below). We
set the poverty line at 200 monetary units. To draw the TIP curves of absolute poverty gaps, simply type
. generate tip = (200 - eqinc)*(eqinc<=200)
. glcurve tip , gl(tip) p(tipp) sort(eqinc) by(owner) split
> xlabel(0,0.25,0.50,0.75,1) ylabel
tip[Tenant] ∙ tip[Owner]
I
I
0 .25 .5 .75 1
Population Share, p_i
Three I's of Poverty Curves
Figure 4. TIP curves of absolute poverty gaps for home owners and renters.
Imagine now that we consider setting a lower poverty line for households that own their houses, e.g., 170 monetary units.
We want to construct TIP curves of relative poverty gaps:
. generate tiprel = (1 - (eqinc/200))*(eqinc<=200) if owner==0
. replace tiprel = (1 - (eqinc∕170))*(eqinc<=170) if owner==l
. glcurve tiprel , gl(tipr) p(tipp) replace sort(eqinc) by(owner)
> split xlabel(0,0.25,0.50,0.75,1) ylabel
(Graph on next page)