Titre
Migrations between Africa and Europe - MAFE Ghana (2009-2010)
Procédure d'échantillonnage
Probability: Stratified
GHANA
A three-stage stratified random sample was used. At the first stage, primary sampling units (census district) were selected randomly with varying probabilities. At the second stage, households were selected randomly in each of the selected primary sampling units (PSUs). At the third stage, individuals were selected within the households.
a) Selection of primary sampling units (first stage)
For Ghana, the target areas were the cities of Accra and Kumasi. In each of the cities, a sampling frame of primary sampling units was prepared. In Senegal and Ghana, recent censuses were available and served as sampling frames at the first stage.
At the first stage, census enumeration areas were randomly selected. In Ghana, 80 enumeration areas were selected with a probability proportional to size. As no information was available for stratifying, the sample was not stratified in the first stage in Ghana.
b) Selection of households (second stage)
A listing operation was carried out in each of the selected survey sites to prepare the sampling frame of households. The listing consisted in enumerating all the households in the selected sites, and in identifying whether these households included migrants of not. In DR Congo and Ghana, three categories of households were distinguished (households with return migrants, with migrants abroad, and without migrants). 8 households were selected in each of the 3 strata (if less than 8 households were available in one or several strata, the remaining households were selected in the other stratum). The sampling rate was higher in strata of households with migrants, in order to get a sufficient sample of such households.
c) Selection of individuals (third stage)
In each of the selected households, one or several respondents were selected among the eligible people (people aged between 25 and 75, and born in the origin country). In DR Congo and Ghana, all the return migrants and partners of migrants currently abroad were selected. In addition, one other eligible member was randomly selected. A special tool had been designed so that the interviewers could randomly select the people during the fieldwork.
Two types of questionnaires were used in the departure countries: the household questionnaire and the individual life history questionnaire.
- The first questionnaire was used among a representative sample of households in the target region.
- The second questionnaire was used among a sample of individuals in the selected households, targeting both return migrants and non-migrants. The household questionnaire was thus used as the sampling frame for the selection of individual respondents.
EUROPE
The objective of the survey was to obtain a sample 'as representative as possible' of the African populations (Congolese, Ghanaian, Senegalese) in the destination countries (150 individuals per origin and destination country). The way the sample was constituted may vary across countries, but some common principles were respected:
- The composition of the sample should be as close as possible to the population of (Congolese, Ghanaian, Senegalese) migrants in the country in terms of gender, geographic distribution, age, socio-economic category or occupation.
- One exception: the sample should be gender balanced. Males and females should be equally represented in order to allow gender analyses.
- Samples in origin and destination may be linked, but migrants with weak or no relationships at origin should not be excluded from the sample.
- Both documented and undocumented migrants should be represented in the sample.
As no suitable frame was available to select randomly individual respondents in five of the six European countries (Spain being the exception), it was decided to use quota sampling. In all the countries, the quotas were set by age and gender at least. In the UK, the place of residence was also used in the quotas.
In the Netherlands, sub-regions concentrating the majority of migrants were selected. In the United Kingdom, the surveys were concentrated in the London area and in the places where Ghanaian migrants were living.
Randomness was also included in the samples in different ways. For instance, in Belgium, a random sample of places was selected according to the number of people of Congolese origin living in these places. Respondents were selected in these places. The combination of different recruitment methods also ensured that different types of persons had a non zero probability of being included in the sample. For instance, some respondents were recruited in public spaces (street, metro station, hairdresser...), others were randomly selected from list of volunteers identified in churches...
*The Netherlands*
- Target areas: 3 cities (in 3 different provinces): Amsterdam, The Hague and Almere
- Sample size: 272
- Quotas: By age, gender
- Recruitment methods: Public spaces, churches, snowballing, interviewers' contacts
*United Kingdom*
- Target areas: Whole country
- Sample size: 149
- Quotas: By age, gender and place of residence
- Recruitment methods: Public spaces, churches, snowballing, interviewers' contacts