| 1. |
- Barclay, Kieron, 1986-, et al.
(författare)
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Birth order and mortality : a population-based cohort study
- 2015
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Ingår i: Demography. - : Duke University Press. - 0070-3370 .- 1533-7790. ; 52:2, s. 613-639
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Tidskriftsartikel (refereegranskat)abstract
- This study uses Swedish population register data to investigate the relationship between birth order and mortality in adulthood over the ages 30 to 69 for Swedish cohorts born between 1938 and 1960, using a within-family comparison. The main analyses are conducted with discrete-time survival analysis using a within-family comparison, and the estimates are adjusted for age, mother's age at the time of birth, and cohort. Focusing on sibships ranging in size from two to six, we find that mortality risk in adulthood increases with later birth order. The results show that the relative effect of birth order is greater amongst women than amongst men. This pattern is consistent for all the major causes of death, but is particularly pronounced for mortality attributable to cancers of the respiratory system, and external causes. Further analyses where we adjust for adult socioeconomic status and adult educational attainment suggest that social pathways only mediate the relationship between birth order and mortality risk in adulthood to a limited degree.
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| 2. |
- Barclay, Kieron, 1986-
(författare)
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A within-family analysis of birth order and intelligence using population conscription data on Swedish men
- 2015
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Ingår i: Intelligence. - : Elsevier BV. - 0160-2896 .- 1873-7935. ; 49, s. 134-143
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Tidskriftsartikel (refereegranskat)abstract
- This study examines the relationship between birth order and intelligence in Sweden. This research question has been of interest for decades, but only one study using a sibling comparison design has found that birth order has a negative effect on intelligence. The data used in this study is Swedish administrative register data, with data on cognitive ability drawn from the military conscription register for men born 1965 to 1977. Within-family comparison linear regression models are used to estimate the difference in cognitive ability by birth order amongst brothers. I find that there is a negative relationship between birth order and cognitive ability. This is consistent in sibling-group-size-specific analyses of sibling groups with two through to six children. Further analyses demonstrate that this negative relationship between birth order and intelligence is consistent in different socioeconomic status groups, and amongst individuals born in the 1960s and 1970s. Analyses of brothers in two-child sibling groups show that the relationship between birth order and intelligence varies by the birth interval. Second borns have a statistically significantly lower cognitive ability score if the birth interval is up to six years, but not if it is longer.
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| 3. |
- Barclay, Kieron, 1986-
(författare)
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Birth Order and Educational Attainment : evidence from Fully Adopted Sibling Groups
- 2015
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Ingår i: Intelligence. - : Elsevier BV. - 0160-2896 .- 1873-7935. ; 48, s. 109-122
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Tidskriftsartikel (refereegranskat)abstract
- This study uses data on fully adopted sibling groups to test whether the explanation for the consistently observed negative effects of birth order are physiological or social in origin. Swedish administrative register data is used to construct full sibling data for cohorts born 1960 to 1982. Using a within-family comparison approach, I compare adopted siblings of different adopted birth order to one another to see whether birth order amongst adopted children (N=6,968) is associated with educational attainment by age 30, and the likelihood of having entered tertiary education by age 30. These same within-family comparison analyses are also performed on siblings in fully biologically related sibling groups (N=1,588,401). I find that there is a negative relationship between adopted birth order and both educational attainment and the likelihood of entering tertiary education in fully adopted sibling sets. These findings strongly suggest that differences in educational attainment by birth order are driven by intrafamily social dynamics. I also conduct additional analyses in fully adopted sibling groups where age order and adoption order are reversed to test whether there is evidence for tutoring by siblings. These results do not indicate clear support for any tutoring effect.
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