in collaboration with other international agencies, it seeks to reduce the untimeliness of data and poor data quality with a less expensive alternative optimizing the sampling procedure and the structure of the questionnaire (Ajayi, 2006; Zoyem et al, 2008). Besides the core modules on household characteristics and consumption behavior, each country can implement additional modules according to its specificities. In the QUIBB for Burundi, questions about displacement and return were included. The sample consists of 6,700 households. The QUIBB sample is characterized by two-stage cluster sampling. In the first stage, 548 sous-collines<sup>11</sup> were sampled and in the second stage, 15 households were sampled in each primary unit.<sup>12</sup> From the original data set, we applied a standard data cleaning process, where missing observations, data entry errors, potential measurement errors, distillation errors and outlier from unusual consumption were deleted.

The second round, undertaken by the authors in April 2010, only retained three provinces of the QUIBB sample: Bubanza, Bujumbura Rural, and Cibitoke, located in the North-West of the country. The choice of these provinces is justified by the concentration of ex-combatants in these three provinces in combination with high level of violence in the region over the last years, as well as by budgetary constraints. We traced 1284 households which were interviewed for the QUIBB survey in the three provinces of interest. A total of 1064 (or 83%) households were found and interviewed in 85 collines.<sup>13</sup> We examine issues related to attrition more closely in section 3.2.

In order to maximize the reliability of the data, we trained interviewers for a week. Interviews were conducted in Kirundi, the local language. After the training, interviewers were selected on the basis of an exam and simulated interviews. The questionnaire was then tested during a pilot study in a colline that was not included in our sample. We assigned teams of five interviewers, each including a team leader and at least two women. Each interviewer did two interviews per day on average. The questionnaires were then checked for accuracy and entered in a CS-PRO program by data entry agents. We checked the accuracy of entry ex-post, too.

Community Data. During the 2010 survey, enumerators also undertook a community survey in each colline. This survey included data on past violence, public services, and community initia-

> 11There are four administrative levels in Burundi: the province, the commune (translated _“municipality”_ ), the colline (translated _“hill”_ ) and the sous-colline (translated _“sub-hills”_ ).

> 12The QUIBB survey used the same sampling strategy as the Multiple Indicator Cluster Survey (MICS), collected in September 2005 by UNICEF. The MICS survey mostly focuses on health and gender issues, and contains little useful information about economic outcomes. The sampling weights of the MICS survey will accounted for in the empirical analysis (results do not change without taking into account these sampling weights).

> 13There were three collines in which we could not trace households, all located in Bujumbura Rural. In two collines, the villagers reported not to know the households, either because they had migrated or were invented by 2005 interviewers. The remaining colline was not secure enough to conduct the survey.

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