Survey ID Number
SLV_2016_ES_v01_M
Title
Enterprise Survey 2016
Sampling Procedure
Three levels of stratification were used in this country: industry, establishment size, and region.
Industry stratification was designed in the way that follows: the universe was stratified into four manufacturing industries and two services industries- Food and Beverages (ISIC Rev. 3.1 code 15), Textiles and Garments (ISIC codes 17 and 18), Furniture (ISIC code 36), Other Manufacturing (ISIC codes 16, 19-35, 37), Retail (ISIC code 52) and Other Services (ISIC codes 45, 50, 51, 55, 60-64, and 72).
Size stratification was defined as follows: small (5 to 19 employees), medium (20 to 99 employees), and large (100 or more employees).
Regional stratification for the El Salvador ES was done across four regions: the San Salvador Metropolitan Area, Greater San Salvador (municipalities of Sensuntepeque, Cojutepeque, Ciudad Arce, Colon, La Libertad, Quezaltepeque, San Juan Opico, Olocuilta, Zacatecoluca, Santo Tomas, and San Vicente), West (Ahuachapan, Chalchuapa, Metapan, Santa Ana, and Sonsonate) and East (La Union, Santa Rosa de Lima, San Francisco Gotera, San Miguel, and Usulutan).
The sample frame consisted of listings of firms from two sources: The panel firms list of 360 firms from the El Salvador 2010 ES was used. For fresh firms (i.e., firms not covered in 2010), firm data from Dirección General de Estadística y Censos (DIGESTYC) was used.
The quality of the frame was assessed at the onset of the project through visits to a random subset of firms and local contractor knowledge. The sample frame was not immune from the typical problems found in establishment surveys: positive rates of non-eligibility, repetition, non-existent units, etc. In addition, the sample frame contains no telephone/fax numbers so the local contractor had to screen the contacts by visiting them. Due to response rate and ineligibility issues, additional sample had to be extracted by the World Bank in order to obtain enough eligible contacts and meet the sample targets.
Given the impact that non-eligible units included in the sample universe may have on the results, adjustments may be needed when computing the appropriate weights for individual observations. The percentage of confirmed non-eligible units as a proportion of the total number of sampled establishments contacted for the survey was 24.9% (349 out of 1399 establishments).