# 4 Data

## 4.1 Sampling and Surveys

To understand the project’s development impacts, the State Government and the World Bank designed a comprehensive impact evaluation survey in 2004, with the aim of quantifying the project’s social and economic benefits and identifying the underlying causal chains between the project and potential outcomes. The surveys were administered at different times, due to the variation in project execution schedules. The analysis has thus been divided to reflect these differences and to exclude different time-fixed effects, pairing the Southeast and Bico do Papagaio regions, and the Northeast and Jalapão regions.

<u>Surveys in the Southeast and Bico do Papagaio. For the first group, baseline data were collected</u> between September and December 2005 from a total of 1,069 households in 110 communities (Table 1).<sup>14</sup> Works were completed in the Southeast by 2010 and in Bico do Papagaio by early 2011. The follow-up survey was conducted between June and July 2011 and covered 1,001 households in the same municipalities.<sup>15</sup> The sample size was determined based on the preliminary survey of population distribution in the project areas. The sample size was similar for both regions: 529 households were surveyed in 41 communities of the Southeast region, and 540 households in 69 communities were covered in the Bico do Papagaio region. The total sample size was determined based on the standard power calculations, which indicate that a sample of 1,500 households would be sufficient. The baseline survey is supportive of this. For instance, the average travel time was 84 minutes, with a standard deviation of 87.1. Under standard assumptions (power=0.8; Type I error=0.05), it should be enough to detect a more than five percent improvement in travel time. The sample size of each region was decided based on population data. The subsample size of each community was then determined in proportion to the number of households that it contained.

<u>Surveys in the Northeast and Jalapão. For the second group, the baseline data were collected between</u> May and November 2008. The sample was relatively smaller than in the first group because the density of population is lower in these regions. In total, 422 households in 110 communities were interviewed (Table 2): 170 households in 27 communities of the Jalapão region and 252 households in 46 communities of the Northeast region. Works in the Northeast and Jalapão were completed, for the most part, in late 2011. Accordingly, the follow-up survey, conducted from October to December 2012, covered 319 households: 290 in the Northeast and 29 in Jalapão.

**Table 1: Sample size for Bico do Papagaio and Southeast Regions (Group 1)**

|Region|Treatment<br>t=0<br>t=1|Cont<br>t=0|rol<br>t=1|R|ural Popul<br>2000|ation<br>2010|
|---|---|---|---|---|---|---|
|Southeast|529|471|||43,508|34,029|
|Bico doPapagaio|109|117|431|413|62,768|67,000|
|Total|638|588|431|413|||

**Table 2: Sample size for Jalapão and Northeast Regions (Group 2)**

||Treatment|Control||Rural Population|
|---|---|---|---|---|
|Region|t=0<br>t=2|t=0|t=2|2000<br>2010|

14 The term “community” does not cover an administrative or jurisdictional reality. For the purpose of the survey, the term “community” covered the cluster of residents along a road segment where the works were executed. It often corresponds to the boundaries of local business associations, if any.

15 The follow-up survey does not cover 11 relatively small municipalities that were included in the baseline survey.

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