Ghana - Enterprise Survey 2007

The sample for registered establishments in Ghana was selected using stratified random sampling. Three levels of stratification were used in the Ghana sample: firm sector, firm size and region.

The survey targeted establishments located in Accra, Kumasi, Takoradi, and Tamale in the following industries (according to ISIC, revision 3.1): all manufacturing sectors (group D), construction (group F), retail and wholesale services (sub-groups 52 and 51 of group G), hotels and restaurants (group H), transport, storage, and communications (group I), and computer and related activities (sub-group 72 of group K).

Size stratification was defined following the standardized definition used for the Enterprise Surveys: micro (1 to 4 employees), small (5 to 19 employees), medium (20 to 99 employees), and large (more than 99 employees). For stratification purposes, the number of employees was defined on the basis of reported permanent full-time workers.

A satisfactory list of establishments was sourced from the Ghana Statistical Service. This list was used to set the target sample size for each stratum. During the survey period, the master list was updated as new information regarding establishments that had closed or were out-of-scope was gathered. The final population size in all strata and locations was 22123, with the vast majority of establishments operating in the micro and manufacturing strata.

In Ghana, the survey included panel data collected from establishments surveyed in the 2003 Oxford Investment Climate Survey (ICS) of Ghana. That survey included establishments in all four manufacturing strata distributed across the entire country. In order to collect the largest possible set of panel data, an attempt was made to contact and survey every establishment in the panel, provided it was located in one of the four cities covered by this survey, it operated in the universe under study, and that the number of panel firms of a certain size in a given industry in a given city did not exceed the number of establishments in the corresponding sample structure. The remainder of the sample (including the entire rest of universe and retail sample in each city) was selected at random from the master list by a computer program.

In this survey, the micro establishment stratum covers all establishments of the targeted categories of economic activity with less than 5 employees. Due to difficulty to obtain trustworthy information from official sources about micro establishments, the implementing agency (EEC Canada) selected an aerial sampling approach to estimate the population of establishments and select the sample in this stratum for all regions of the survey.

First, to randomly select individual micro establishments for surveying, the following procedure was followed: i) select districts and specific zones of each district where there was a high concentration of micro establishments; ii) count all micro establishments in these specific zones; iii) based on this count, create a virtual list and select establishments at random from that virtual list; and iv) based on the ratio between the number selected in each specific zone and the total population in that zone, create and apply a skip rule for selecting establishments in that zone.

The districts and the specific zones were selected at first according to national sources. The implementing team then went in the field to verify these national sources and to count micro establishments. Once the count for each zone was completed, the numbers were sent back to EEC head office in Montreal.

At the head office, the count by zone was converted into one list of sequential numbers for the whole survey region, and a computer program performed a random selection of the determined number of establishments from the list. Then, based on the number that the computer selected in each specific zone, a skip rule was defined to select micro establishments to survey in that zone. The skip rule for each zone was sent back to the EEC field team.

In Ghana, enumerators were sent to each zone with instructions to how to apply the skip rule defined for that zone as well as how to select replacements in the event of a refusal or other cause of non-participation.