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Sungcheol Yun

Publications and source records attributed to Sungcheol Yun.

2 recordsLinked to original sources

Robust estimation in mixed linear models with non-monotone missingness.

We introduce a model to account for abrupt changes among repeated measures with non-monotone missingness. Development of likelihood inferences for such models is hard because it involves intractable integration to obtain the marginal likelihood. We use hierarchical likelihood to overcome such difficulty. Abrupt changes among repeated measures can be well described by introducing random effects in the dispersion. A simulation study shows that the resulting estimator is efficient, robust against misspecification of fatness of tails. For illustration we use a schizophrenic behaviour data presented by Rubin and Wu.

Computer Simulation↗

Rising rates, changing relationships: caesarean section and its correlates in South Korea, 1988-2000.

OBJECTIVE: To examine the trends in the relationship between caesarean section rates in South Korea and its correlates. DESIGN: Five rounds (1988, 1991, 1994, 1997 and 2000) of population-based National Fertility and Family Health Survey of South Korea. SETTING: South Korea. Sample Mothers (N= 9184) aged 15-44 years. METHODS: Caesarean rates were calculated according to correlates and then directly adjusted to five-year age and parity groups. Distribution of all samples (9184 mothers) was standard, producing age- and parity-adjusted caesarean rates. Linear trends of correlates with caesarean rates were examined for ordinal variables such as education, income, urbanisation level (area of residence) and level of prenatal visits. MAIN OUTCOME MEASURE: Age- and parity-adjusted caesarean section rates. RESULTS: As caesarean rates rose by year, the relationship of caesarean section with education, occupation and area of residence has been reversed. Associations between caesarean rates, income level, place of delivery and level of prenatal visit were found in 1988 but disappeared by 2000. In 2000, relatively low caesarean rates were found in variables that will be more prevalent in the future, such as higher maternal education, higher maternal occupation and residence in big cities. CONCLUSION: Caesarean rates may have reached a plateau in South Korea. No maternal or health service factors were detected to further increase the proportion of caesarean deliveries.

Adolescent↗