Integrated Household Survey 2003-2004

The primary source of the Sampling Frame was the 1985 Population Census of Sierra Leone. The country is divided into the Northern, Southern, and Eastern Provinces and the Western Area. Each Province/Area is divided into Districts/Wards. The Districts are further divided into Chiefdoms, Towns and Villages hierarchically. The Chiefdoms and Towns are divided into Census Enumeration Areas (EAs), which formed the Primary Sampling Unit, from which information on the number of households and population in each EA was derived. Each District or Ward is stratified into Rural and Urban Areas. The Ultimate Sampling Unit was the Household. The overall sampling frame was stratified into two strata, urban and rural, with sampling carried out separately in each stratum. The Enumeration Area was the Primary Sampling Unit with an average population of 1,645. Based on revised population estimates, about 66% of Sierra Leoneans households live in the rural areas so the sample stratification ensured that 66% of selected households came from the rural areas. In the selection of the 226 Enumeration Areas from the 2,553 Enumeration Areas for the Listing of Households, 66 Urban EAs and 160 Rural EAs were selected systematically with a random start and fixed interval of 11. The selection of the EAs within the Urban and Rural list was done to ensure that they were spread out evenly among all the Provinces or Regions in Sierra Leone.

The sample for the Sierra Leone Integrated Household Survey was drawn in two stages with the Enumeration Areas chosen as the Primary Sampling Unit (PSU). A total of 226 EAs were selected systematically out of the 2,538 EAs without probability proportional to their population size. The second stage involved the listing of all households within each selected EA and randomly selecting 1,300 households in the Urban Area (20 Households per Urban EA) and 2,400 households in the Rural Area (15 Households per Rural EA) using a table of Random Numbers. For each Enumeration Area, eight substitute Households were selected. The existing Sampling Frame is based on the 1985 Population Census. Sierra Leone is divided into the Southern, Eastern, Northern Province and the Western Area with each divided into Districts / Ward. The Districts / Wards are divided into Census Enumeration Areas from which information on the number of Households are obtained. Each District is stratified into Rural and Urban. The 2,553 Enumeration Areas (EAs), constituting 1,320 Urban and 2,400 Rural EAs was created out of the 1985 Population Census and used as the Sampling Frame for the Sierra Leone Integrated Household Survey. The Sampling Design adopted for the Survey was a 2 - Stage Stratified Sampling.

(a) Stage 1 constituted 226 Enumeration Areas selected from the 2553 Enumeration Areas. In Stage 1, the Sampling of 2553 / 266 = approximately 11 was determined and a random number between 1 and 11 inclusive selected. Starting with that randomly selected number we systematically select every 11th EA to give the required 226 EAs. The Sample was not selected with Probability Proportional to Population Size since the population figures are based on the 1985 Census and out of date. The List of Households and Maps existing at the start of the Survey were derived from the 1985 Population Census. These Frames are more than 17 years old and significant changes have taken place, especially in the Urban Areas, because of population growth, migration and other factors. Since to update the Frame and Maps for all the EAs will be too expensive, Listings of all Households in the 226 EAs was done in order to control both Sampling and Non-Sampling Errors. A Household is defined as a group of related and unrelated persons living in a dwelling unit, eating from the same pot and sharing the common housekeeping arrangement. The Household member, with some exceptions, is a normal resident of the house who spent more than nine months in the household during the past 12 months.

(b) Stage 2 constituted the selection of 20 Households from each of the 66 Urban EA to give 1,320 Urban Households, and 15 Households from each of the 160 Rural EAs to give 2,400 Rural Households. Thus, the total number of Households drawn for the Survey, using 2-Digit and 3-Digit Tables of Random Numbers, was 3720.