title: Factors influencing enrollment: a case study from Birth to Twenty, the 1990 birth cohort in Soweto-Johannesburg.
abstract: Longitudinal studies offer significant advantages in rendering data commensurate with the complexity of human development. However, incomplete enrollment and attrition over time can introduce bias. Furthermore, there is a scarcity of evaluative information on cohorts in developing countries. This paper documents various strategies adopted to minimize loss to follow up and describes a retrospective analysis of a small group of families who were missed during initial enrollment and through several subsequent rounds of data collection of the Birth to Twenty (BT20) birth cohort in Soweto-Johannesburg, South Africa that began in 1990. A purposive case study approach was used, and 10 of the 119 families missed at enrollment were interviewed to investigate why these families were not enrolled into the study. The findings demonstrate that high mobility, both within urban areas and between urban and rural areas, are a major challenge for longitudinal studies in densely populated urban areas. In addition, enrollment was also affected by individuals changing their names, largely motivated to facilitate access to employment under Apartheid, as well as varying motivations for participating in research. Longitudinal studies in the developing country context must be mindful of the political, social and economic climate that influences enrollment and ongoing cohort maintenance.
authors.affiliation: Child Youth Family and Social Development, Human Sciences Research Council, Private Bag X07, Dalbridge 4014, South Africa. lrichter@hsrc.ac.za
authors.forename: Linda M
authors.initials: LM
authors.lastname: Richter
authors.forename: Saadhna
authors.initials: S
authors.lastname: Panday
authors.forename: Shane A
authors.initials: SA
authors.lastname: Norris
mesh_terms: D000293:Adolescent; D000328:Adult; D001719:Birth Certificates; D002391:Catchment Area, Health; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005191:Family Characteristics; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D010352:Patient Dropouts; D010358:Patient Participation; D011157:Population Dynamics; D035842:Research Subjects; D012923:Social Class; D013019:South Africa / Q000453:epidemiology; D014505:Urban Population; D055815:Young Adult