Sampling Procedure
The Informal Surveys are conducted in selected urban centers, which are intended to coincide with the locations for the implementation of the main Enterprise Surveys. The overall number of interviews is pre-determined.
In Guatemala, the urban centers identified were Guatemala City and Quetzaltenango. The target sample for Guatemala City was 184 interviews and 120 interviews in Quetzaltenango.
Sampling in the Informal Surveys is conducted within clearly delineated sampling zones, which are geographically determined divisions within each urban center. Sampling zones are defined at the beginning of fieldwork, and are delineated according to the concentration and geographical dispersion of informal business activity.
The number of sampling areas, and the geographical area they contain, is determined with the goal that each sector will yield four effective interviews.
In Guatemala, each sampling area was designed to contain a physical area, on average, of no less than the equivalent of eight city blocks. These sampling areas may or may not correspond to the administrative districts of the urban center.
Moreover, in order to ensure a degree of geographical dispersion, each urban center was divided into distinct zones. In both Guatemala City and Quetzaltenango, a central zone was identified as well as four quadrants, north, south, east, and west.
In Guatemala City, 46 primary sampling areas (184/4 = 46) were required; 30 primary sampling areas (120/4 = 30) were necessary in Quetzaltenango.
The sampling areas were distributed among the zones according to estimates - determined in conversations with the local contractor - of the concentration of informal activity in each geographical zone. In Guatemala City, the distribution of the sampling areas was as follows: central - 12 sampling areas; north - 5 sampling areas; west - 5 sampling areas; south - 12 sampling areas; and east - 12 sampling areas. In Quetzaltenango, the distribution was: central - 7 sampling areas; north - 5 sampling areas; west - 7 sampling areas; south - 5 sampling areas; and east - 6 sampling areas.
In order to provide information on diverse aspects of the informal economy, the sample is designed to have equal proportions of services and manufacturing (50:50). These sectors are defined by responses provided by each informal business to a question on the business's main activity included in the screener portion of the questionnaire.
As a general rule, services must constitute an ongoing business enterprise and so exclude the sale of manual labor Manufacturing activity in the informal sector includes business activity requiring inputs and/or intermediate goods. Thus, for example, the processing of coffee, sugar, oil, dried fruit, or other processed foods is considered manufacturing, while the simple selling of these goods falls under services. If an informal business conducts a mixture of these activities, the business is considered under the manufacturing stratum.
Each sampling zone was designed with the goal of obtaining two interviews in services and two interviews in manufacturing. In order to ensure a degree of geographical dispersion within each sampling zone, two starting points were identified. Each starting point was designed to correspond to four city blocks, which were numbered sequentially.
Proceeding from each starting point, interviewers were instructed to begin on the first block (i.e, 1 or 5), defining the starting block and corner. Each interviewer was instructed to attempt to achieve two interviews from each starting point, ideally one interview in manufacturing and one in services.
Interviewers were instructed to proceed clockwise around block 1 from Starting Point A; if the target interviews were not achieved, interviewers proceeded to block 2, Starting Point A, and so forth until completing a circuit of block 4. After achieving two interviews from starting point A, interviewers were instructed to cease work in the blocks assigned to that given starting point and repeat the same procedure from starting point B, beginning with block 5.
Using the local knowledge of enumerators and the implementing contractor to help identify informal business activity, within each block all houses and shops were checked for unregistered businesses, following the pre-fixed route described above, until the allotted quota of interviews for the sampling area was reached. The implementing contractor reported that informal businesses were identified frequently as those that did not display commercial registration or sanitation permits, as required by Guatemalan law. Informal firms were also frequently identified as those issuing receipts (if at all) without an NIT (Número de Identificación Tributaria), which Guatemalan law requires on sales records.
Each sampling area, including its two starting points, were delineated using Google maps (or Google Earth), with the GPS coordinates of the starting points being systematically recorded.
Additionally, when obtaining a complete interview, the exact address of the informal business (or where the interview took place) was registered by the interviewer. Once in the office, this address was searched in Google maps, and its GPS coordinates were registered in a fieldwork report.
If no address was immediately available, using local knowledge, the GPS coordinates were determined using imaging via Google maps.
In order to preserve confidentiality, the exact coordinates of businesses are not published.
Complete information regarding the sampling methodology can be found in "Description of Guatemala Informal Survey Implementation" in "Technical Documents" folder.