# **4. The Data**

The empirical analysis of household labor supply and income responses to changes in formal property rights relies on a data survey developed especially and exclusively for this paper, in the City of Osasco, an important town in the São Paulo metropolitan area with a population of 654,000 people.

The federal government has chosen Osasco, as one of the participants of the " _Papel Passado_ " - a program that intends, as mentioned earlier in the paper, to provide land titles to families living under illegal conditions - given its relevant economic and social role.

The city of Osasco has 30,000 people (about 6,000 families) living under informal conditions, which represents almost 4.5% of its total population. The program timetable for Osasco establishes that all the communities living in illegal conditions will be part of the " _Papel Passado_ " during the period between 2007 and 2014 (the main reason that all communities are not receiving the land title at the same time is becuase fiscal resources are limited). Officially, as released by the Osasco City Hall, the priority follows random criteria. Unofficial sources from local communities in Osasco express the feelings that a "political" agenda is present in the decision.

The first community to receive the land title was _Jardim Canaã_ , in 2007, which has 500 families. The closest neighbor of _Jardim Canaã_ is a community called _DR_ , with 450 families. The _DR_ 's households will be part of the " _Papel Passado_ " program schedule in 2011. Hence, the data of this particular paper consist of 326 households distributed across _Jardim Canaã_ and _DR_ (185 from _Jardim Canaã_ and 141 from _DR_ ).

# **4.1 Minimizing Endogeneity Bias Concerns**

Given the nature of the research conducted in the city of Osasco, some steps were taken to minimize the bias related to the data collected.

First of all, a technique from Bolfarine & Bussab (2005) was used to choose randomly 326 sample households. The approach was basically to choose the first 150 households (from the _Canaã_ and _DR_ ) that have the closest birth dates (day and month) in comparison with the three field researchers that conducted the survey interviews (important to mention that the field researchers are not from Osasco). Each researcher got 50 names initially as first base. Additionally, after reaching each of those households, they could go and pick the third and the fifth neighbor on the right hand side.

Secondly, Heckman & Hotz (1989) states that constructing counterfactuals is the central problem in the literature evaluating social programs given the impossibility of observing the same person in both states at the same time. The goal of any program evaluation is to compare only comparable people. An important step to minimize such issue in this study was to use a comparison between those two neighbors ( _Jardim Canaã_ and _DR_ ) with very similar characteristics. _Canaã_ and _DR_ are not only official neighbors but there is no physical "borderline" among them, both are geographically united (if someone walks there, it is hard to identify the boundaries -- even for the local households).

One of them, _Jardim Canaã_ , fortunate to receive the titles in 2007, is qualified, for the paper proposal, as the main sample. The other, _DR_ , only part of the program schedule in 2011, became the control group. This approach enables a comparison of households in a neighborhood reached by the program with households in a neighborhood not yet reached and makes it possible to produce a panel of data.

Another aspect to be mentioned about the data collected is that it produced a unique match within the same geographic area, which helped to ensure that comparison units come from the same economic environment. Rubin & Thomas (2000) indicate that impact estimates 10