based on full (unmatched) samples are generally more biased, and less robust to missspecification of the regression function, than those based on matched samples.

Given such conditions, the data were produced from a two-stage survey focused on the property right issue. However, to minimize bias, the way that survey was prepared and conducted by the researchers does not provide any direct information for the households on what exactly the research is about. Officially for the people interviewed, the study was about general living conditions in the City of Osasco.

The survey was based on a 39-question questionnaire applied to the 326 families randomly sampled as described above. The survey instrument, in many of its questions and methodologies, closely mirrors the IBGE Living Standards Measurement Survey (PNAD - _Pesquisa Nacional de Amostra de Domicílios do Instituto Brasileiro de Geografia e Estatística_ ) in content, and therefore contains a variety of information on household and individual characteristics. In addition, there are six questions designed to provide information on a range of economic, social and personal benefits associated with property formalization. (See Appendix A for the complete stage I and stage II questionnaires.) The first stage of the survey was conducted in March 2007, before titles had been issued to _Jardim Canaã_ , and the second collected in August 2008, almost a year and a half after the first titles had been issued (with exactly the same households and with 98.0% recall -- or 2.0% missing, which means that almost all the households interviewed in the first survey were found and interviewed during the second stage). The reason for the time gap was to give the an opportunity to all the households interviewed during the first survey stage to have at least 1 year with the land title. The exactly dates that each household interviewed received the title were provided by the 2nd _Cartório de Osasco_ (2nd Osasco's Office of Registration) along with the formal authorization from the Osasco's City Hall to conduct the research.

Heckman & Hotz (1989) add that is not necessary to sample the same persons in different periods -- just persons from the same population. This particular survey instrument design has clearly the advantage that the same households were tracked over time to form a panel data set. Ravallion _et al._ (1995) argue that making a panel data with such characteristics should be able to satisfactorily address the problem of miss-matching errors from incomplete data, a very common issue regarding public policy evaluation.

Furthermore, it is also important to emphasize again another aspect that helps minimize the selection bias. Based on the first survey, 95.0% of the survey participants (from _Canaã_ and _DR_ ) did not expect to receive any land title, i.e., they were not aware of " _Papel Passado_ " and the meaning of it. Such lack of information about the subject provides the study a nonbias aspect regarding the importance of property rights because it avoids a potential behavior deviation from households included in the program.

Finally, the study also tracks the households that moved outside both communities to check if the land title effect stands. From the original sample only 8.0% of the households that received the land title have moved away from _Canaã_ (one of the main concerns from local authorities in Osasco was that most citizens would receive the land title, sell the property right away and return to an informal living conditions and that not has been materialized). From the control group, only 1 household (out of 140) has moved during the same period.

# **5. Basic Findings – Child Labor Force**

This study has used basically four questions to address the issue of child labor using the survey. The first question was: _“Do you have any children?”_ (Please refer to Appendix A for the complete stage I and stage II questionnaires.) Of the combined sample and control group, about 75.0% of the households said they have children (about 73.0% of the sample and 76.0% of the control group).

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