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| 2. |
- Chaparro, Pia, et al.
(författare)
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Regional inequalities in pre-pregnancy overweight and obesity in Sweden, 1992, 2000, and 2010
- 2015
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 43:5, s. 534-539
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Tidskriftsartikel (refereegranskat)abstract
- Aims: To investigate regional differences and time trends in women's overweight and obesity in Sweden. Methods: Using data from the Swedish Medical Birth Register (women aged 18 years, first pregnancy only) and the Total Population Register accessed through the Umea SIMSAM Lab, age-standardized prevalence of pre-pregnancy overweight/obesity (BMI 25 kg/m(2)) and obesity (BMI 30 kg/m(2)) were estimated by county for the years 1992, 2000, and 2010. Maps were created using ArcMap v10.2.2 to display regional variations over time and logistic regression analyses were used to assess if the observed trends were significant. Results: The prevalence of pre-pregnancy overweight/obesity and obesity increased significantly in all Swedish counties between 1992, and 2010. In 2010, Sodermanland and Gotland exhibited the highest age-standardized overweight/obesity (39.7%) and obesity (15.1%) prevalence, respectively. The sharpest increases between 1992 and 2010 were observed in Vasterbotten for overweight/obesity (75% increase) and in Gotland for obesity (233% increase). Across the years, Stockholm had the lowest prevalence of overweight/obesity (26.3% in 2010) and obesity (7.3% in 2010) and one of the least steep increases in prevalence of both between 1992 and 2010. Conclusions: Substantial regional differences in pre-pregnancy overweight and obesity prevalence are apparent in Sweden. Further research should elucidate the mechanisms causing these differences.
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| 3. |
- Daunfeldt, Sven-Olov, et al.
(författare)
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Central bank independence and price stability : evidence from OECD-countries
- 2008
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Ingår i: Oxford Economic Papers. - Oxford : Oxford University Press (OUP). - 0030-7653 .- 1464-3812. ; 60:3, s. 410-422
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we use a non-parametric regression method to compare the transition process from high to low inflation with the implementation dates of central bank independence reforms. In most countries, price stability is achieved before more independence is given to the central bank. Moreover, for those countries which have implemented a central bank independence reform under a high inflation regime, no evidence is found that the reforms have actually led to price stability. This suggests that the credibility of a low inflation goal can be achieved without institutional reforms which grant the central bank more independence from the political policymakers.
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| 4. |
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| 5. |
- de Luna, Xavier, 1968-, et al.
(författare)
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Can adult education delay retirement from the Labour Market?
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Several studies have suggested that education is associated with later retirement from the labour market. In this paper, we examine whether adult education, involving enrolees aged 42 or above, delays retirement to potentially increase labour force participation among the elderly. With Swedish register data of transcripts from adult education and an-nual earnings, which encompasses 1979-2004 and 1982-2004 respectively, we exploit the fact that adult education is a large-scale phenomenon in Sweden and construct a measure of the timing of the transition from being self-supported by productive work to being supported by pension transfers. We match samples of treated and controls on the propen-sity score and use non-parametric estimation of survival rates. The results indicate that adult education has no effect on the timing of the retirement from the labour force. This can be contrasted with the fact that adult education is one of the cornerstones of the OECD strategy for “active ageing” and the European Union’s “Lisbon strategy” for growth and jobs.
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| 6. |
- de Luna, Xavier, 1968-, et al.
(författare)
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Non-parametric inference for the effect of a treatment on survival times with application in the health and social sciences
- 2010
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Ingår i: Journal of Statistical Planning and Inference. - : Elsevier. - 0378-3758 .- 1873-1171. ; 140:7, s. 2122-2137
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we perform inference on the effect of a treatment on survival times in studies where the treatment assignment is not randomized and the assignment time is not known in advance. Two such studies are discussed: a heart transplant program and a study of Swedish unemployed eligible for employment subsidy. We estimate survival functions on a treated and a control group which are made comparable through matching on observed covariates. The inference is performed by conditioning on waiting time to treatment, that is, time between the entrance in the study and treatment. This can be done only when sufficient data are available. In other cases, averaging over waiting times is a possibility, although the classical interpretation of the estimated survival functions is lost unless hazards are not functions of waiting time. To show unbiasedness and to obtain an estimator of the variance, we build on the potential outcome framework, which was introduced by J. Neyman in the context of randomized experiments, and adapted to observational studies by D.B. Rubin. Our approach does not make parametric or distributional assumptions. In particular, we do not assume proportionality of the hazards compared. Small sample performance of the estimator and a derived test of no treatment effect are studied in a Monte Carlo study.
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| 7. |
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| 8. |
- de Luna, Xavier, 1968-, et al.
(författare)
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Testing for the Unconfoundedness Assumption Using an Instrumental Assumption
- 2014
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Ingår i: Journal of Causal Inference. - : Walter de Gruyter GmbH. - 2193-3677 .- 2193-3685. ; 2:2, s. 187-199
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Tidskriftsartikel (refereegranskat)abstract
- The identification of average causal effects of a treatment in observational studies is typically based either on the unconfoundedness assumption (exogeneity of the treatment) or on the availability of an instrument. When available, instruments may also be used to test for the unconfoundedness assumption. In this paper, we present a set of assumptions on an instrumental variable which allows us to test for the unconfoundedness assumption, although they do not necessarily yield nonparametric identification of an average causal effect. We propose a test for the unconfoundedness assumption based on the instrumental assumptions introduced and give conditions under which the test has power. We perform a simulation study and apply the results to a case study where the interest lies in evaluating the effect of job practice on employment.
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| 9. |
- Holmström, Anna, et al.
(författare)
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SIMSAM-nätverket i Umeå strävar mot att bli ett framstående center för registerforskning som knyter samman barndomen med livslång hälsa och välfärd
- 2011
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Ingår i: SVEPET - Medlemstidning för Svensk Epidemiologisk Förening (SVEP). - Göteborg : Svensk epidemiologisk förening. - 1101-4385. ; 29:3, s. 8-9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Vetenskapsrådets SIMSAM initiativ syftar till att stärka multidisciplinär registerforskning i Sverige. Inom SIMSAM-nätverket i Umeå arbetar vi tvärvetenskapligt med sikte på att utvecklas till ett center med excellens kring mikrodataforskning som knyter samman barndomen med livslång hälsa och välfärd. Just nu fokuserar vi på att få tillgång till sammanlänkade data från ett flertal nationella och regionala register för att komma vidare med vår planerade forskning. Dessutom har Umeå-nätverket nyligen fått i uppdrag att leda den nationella samordningen av SIMSAM initiativet.
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| 10. |
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| 11. |
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| 12. |
- Häggström, Jenny, 1980-, et al.
(författare)
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Estimating prediction error : cross-validation vs. accumulated prediction error
- 2010
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Ingår i: Communications in statistics. Simulation and computation. - : Informa plc.. - 0361-0918 .- 1532-4141. ; 39:5, s. 880-898
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Tidskriftsartikel (refereegranskat)abstract
- We study the validation of prediction rules such as regression models and classification algorithms through two out-of-sample strategies, cross-validation and accumulated prediction error. We use the framework of Efron (1983) where measures of prediction errors are defined as sample averages of expected errors and show through exact finite sample calculations that cross-validation and accumulated prediction error yield different smoothing parameter choices in nonparametric regression. The difference in choice does not vanish as sample size increases.
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| 13. |
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| 14. |
- Josefsson, Maria, 1979-, et al.
(författare)
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Causal inference with longitudinal outcomes and non-ignorable drop-out : Estimating the effect of living alone on cognitive decline
- 2016
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Ingår i: The Journal of the Royal Statistical Society, Series C. - : Oxford University Press (OUP). - 0035-9254 .- 1467-9876. ; 65:1, s. 131-144
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Tidskriftsartikel (refereegranskat)abstract
- We develop a model to estimate the causal effect of living arrangement (living alone versus living with someone) on cognitive decline based on a 15-year prospective cohort study, where episodic memory function is measured every 5 years. One key feature of the model is the combination of propensity score matching to balance confounding variables between the two living arrangement groups—to reduce bias due to unbalanced covariates at baseline, with a pattern–mixture model for longitudinal data—to deal with non-ignorable dropout. A fully Bayesian approach allows us to convey the uncertainty in the estimation of the propensity score and subsequent matching in the inference of the causal effect of interest. The analysis conducted adds to previous studies in the literature concerning the protective effect of living with someone, by proposing a modelling approach treating living arrangement as an exposure.
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| 15. |
- Josefsson, Maria, 1979-, et al.
(författare)
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Genetic and Lifestyle Predictors of 15-Year Longitudinal Change in Episodic Memory
- 2012
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Ingår i: Journal of The American Geriatrics Society. - : Wiley. - 0002-8614 .- 1532-5415. ; 60:12, s. 2308-2312
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To reveal distinct longitudinal trajectories in episodic memory over 15 years and to identify demographic, lifestyle, health-related, and genetic predictors of stability or decline. Design: Prospective cohort study. Setting: The Betula Project, Umeå, Sweden. Participants: One thousand nine hundred fifty-four healthy participants aged 35 to 85 at baseline. Measurements: Memory was assessed according to validated episodic memory tasks in participants from a large population-based sample. Data were analyzed using a random-effects pattern-mixture model that considered the effect of attrition over two to four longitudinal sessions. Logistic regression was used to determine significant predictors of stability or decline relative to average change in episodic memory. Results: Of 1,558 participants with two or more test sessions, 18% were classified as maintainers and 13% as decliners, and 68% showed age-typical average change. More educated and more physically active participants, women, and those living with someone were more likely to be classified as maintainers, as were carriers of the met allele of the catechol-O-methyltransferase gene. Less educated participants, those not active in the labor force, and men were more likely to be classified as decliners, and the apolipoprotein E ɛ4 allele was more frequent in decliners. Conclusion: Quantitative, attrition-corrected assessment of longitudinal changes in memory can reveal substantial heterogeneity in aging trajectories, and genetic and lifestyle factors predict such heterogeneity.
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| 16. |
- Pudas, Sara, et al.
(författare)
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Brain characteristics of individuals resisting age-related cognitive decline over two decades
- 2013
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 33:20, s. 8668-8677
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Tidskriftsartikel (refereegranskat)abstract
- Some elderly appear to resist age-related decline in cognitive functions, but the neural correlates of successful cognitive aging are not well known. Here, older human participants from a longitudinal study were classified as successful or average relative to the mean attrition-corrected cognitive development across 15-20 years in a population-based sample (n = 1561). Fifty-one successful elderly and 51 age-matched average elderly (mean age: 68.8 years) underwent functional magnetic resonance imaging while performing an episodic memory face-name paired-associates task. Successful older participants had higher BOLD signal during encoding than average participants, notably in the bilateral PFC and the left hippocampus (HC). The HC activation of the average, but not the successful, older group was lower than that of a young reference group (n = 45, mean age: 35.3 years). HC activation was correlated with task performance, thus likely contributing to the superior memory performance of successful older participants. The frontal BOLD response pattern might reflect individual differences present from young age. Additional analyses confirmed that both the initial cognitive level and the slope of cognitive change across the longitudinal measurement period contributed to the observed group differences in BOLD signal. Further, the differences between the older groups could not be accounted for by differences in brain structure. The current results suggest that one mechanism behind successful cognitive aging might be preservation of HC function combined with a high frontal responsivity. These findings highlight sources for heterogeneity in cognitive aging and may hold useful information for cognitive intervention studies.
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| 17. |
- Stenberg, Anders, 1966-, et al.
(författare)
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Can adult education delay retirement from the Labour Market?
- 2012
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Ingår i: Journal of Population Economics. - : Springer. - 0933-1433 .- 1432-1475. ; 25:2, s. 677-696
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Tidskriftsartikel (refereegranskat)abstract
- We examine whether adult education delays retirement to potentially increase labour force participation among the elderly, a mechanism suggested in the OECD strategy for “active ageing” and the “Lisbon strategy” of the EU. Using register data from Sweden, we analyse transcripts from adult education for the period 1979–2004 and annual earnings 1982–2004. We match samples of treated individuals, in adult education 1986–1989, and untreated on the propensity score. The timing of exit from the workforce is assessed by non-parametric estimation of survival rates in the labour force. The results indicate no effects of adult education on the timing of retirement.
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