methodology: quantile regression panel data for bolsa familia
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Dario Debowicz explains the methodology behind his analysis of the impact of Bolsa Familia transfers within different municipalities in Brazil. Read the full research at: http://bit.ly/1plN4yITRANSCRIPT
METHODOLOGICAL
PRESENTATION
QUANTILE REGRESSION PANEL
DATA FOR BOLSA FAMILIA SOCIAL
TRANSFERS
Armando Barrientos & Dario Debowicz
BWPI, University of Manchester
CURRENT RESEARCH
The effects of Bolsa Familia social transfers in Brazil on labour supply and school attendance (DFID IRIBA Phase I).
Goal is to analyse the distribution of program outcomes across municipalities in Brazil using quantile regressions, which have not been used in this context...
taking into account the indirect effects of the program on beneficiaries and non-beneficiaries.
controlling for time-invariant conditions at the municipality level.
(partially) addressing the issue of endogeneity in program assignment.
Bolsa Familia is Brazil’s flagship social protection program. Its national budget (0.5% GDP) is allocated among municipalities, mainly as a function of the distribution of pre-program poverty, based on household data. Municipalities then allocate the transfers at the household level. The transfers are conditional on children’s school attendance and health check-ups.
METHODOLOGY AND DATA
Quantile regressions panel data for short period following Abrevaya & Dahl (2008), on municipality-level data.
Our database is constructed using an annual cross-section of a nationally representative household-level survey(PNAD), focusing on the municipalities for which PNAD is representative (273).
We use seven waves to build our panel, from the start of the program (2003) to the last year when the set of surveyed municipalities remains unchanged (2009).
Among the covariates, we include pre-program poverty data used by the Brazilian government to allocate the program quotas among municipalities (PNAD 2001).
Households benefiting from the program are identified via a specific question in the survey (when possible) or via typical transfer values (otherwise).
EMPIRICAL MODEL
𝑄𝜏 𝑦𝑚𝑡 𝑥𝑚𝑡
= 𝑥𝑚𝑡′ 𝛽𝜏 + 𝜓𝜏
𝑡 + 𝑠𝑒𝑡 𝑜𝑓 𝑑𝑖𝑠𝑡𝑟𝑖𝑏𝑢𝑡𝑒𝑑 𝑙𝑎𝑔𝑠
𝑦𝑚𝑡 = 𝐿𝐴𝑚,𝑡 , 𝑆𝐹𝑚,𝑡 , 𝑆𝑀𝑚,𝑡
𝑥𝑚,𝑡 = 𝐵𝐹𝑚,𝑡 , 𝑋𝑂𝑚,0
𝑋𝑂𝑚,0: the other covariates.
PRECISION OF PARAMETER ESTIMATES
Usual bootstrap procedures to calculate standard
errors imbedded in Stata are not consistent for this
method (Abrevaya and Dahl, 2008).
Starting with Abrevaya and Dahl’s bootstrap
estimation procedure, we extend it to include more
than two years and time-invariant regressors, such
as pre-program poverty at municipality level, using
Stata.
RESULTS: FEMALE SCHOOL ATTENDANCE (%) 0
.1.2
.3
Ch
an
ge
(p
.p.)
fo
r 1
p.p
. in
crea
se in
pro
gra
m in
cide
nce
0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1Quantiles
OLS
QRPD
RESULTS: MALE SCHOOL ATTENDANCE (%) -.
10
.1.2
Ch
an
ge
(p
.p.)
fo
r 1
p.p
. in
crea
se in
pro
gra
m inci
de
nce
0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1Quantiles
QRPD
OLS
FINDINGS (1 OF 2) The estimated effect of the municipal coverage of Bolsa Família on the
distribution of female school attendance among conditional quantiles of
outcome indicates significant heterogeneity, in contrast to OLS results.
While point estimates are positive for all conditional quantiles analysed, the
effect is statistically significant (with a ten percent significance level) from
quantile .10 to quantile .40 of the outcome distribution. The maximum is
achieved in quantile .10, where a less than 8 (0.1268-1) percentage point
(p.p.) increase in program incidence is needed to “buy” a p.p. of female
school attendance. This contrasts sharply with the median municipality,
where more than 28 (0.0349-1) p.p. of program incidence are needed for the
same target, or with municipalities in the top of the distribution, where the
program leads to practically no school attendance increases.
FINDINGS (2 OF 2) A formal test of the uniformity of Bolsa Família effects on female school
attendance among quantiles, which we conduct by extending the analysis of
AD, rejects the null of uniformity even at one percent level of significance.
At the same significance level, a test of significance of the correlated random
effects rejects the null of insignificance. This suggests that unobservables
affecting female school attendance may be captured, in part, by repeated
observations on the program incidence, and that results not accounting for
them could lead to a significant bias in the estimation of program effects.
A test of overall significance of the regression does not reject the null of lack
of significance, suggesting significant variation of school attendance was left
unexplained.
With the notable exception of the bottom quantile analysed, the program has
worked to reduce differential outcomes across the conditional schooling
distribution of municipalities. This adds to the evidence in support of Bolsa
Família’s contribution to inclusive growth.
Try to include 2000 census poverty, yearly Bolsa Familia benefits, and
other municipal-level information in our database, for which we are trying
to get the names of the municipalities in PNAD from the Brazilian statistical
office (IBGE).
Future research could look into other program outcomes of interest.
FOLLOWING STEPS AND FUTURE
RESEARCH
RESULTS: LABOR SUPPLY (%)
-.1
0.1
.2
Ch
an
ge
(p
.p.)
fo
r 1
p.p
. in
cre
ase in p
rogra
m incid
ence
0 .1 .2 .3 .4 .5 .6 .7 .8 .9 1Quantiles
OLS
Source: Authors’ quantile regression panel data and OLS regressions. For
quantile regressions, point estimates and 90% and 95% confidence
intervals are included. Municipal cluster standard errors are reported in
parenthesis. All specifications include all regressors as listed in Table A1 in
the Appendix. The sample size is 1,911 municipal-level cases.
QRPD
Antipoverty transfers and inclusive growth in Brazil:
http://bit.ly/1plN4yI
Other working papers from the International Research Initiative on Brazil and
Africa (IRIBA) are available at:
http://www.brazil4africa.org/publications/
WORKING PAPER: