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49 results on '"Schomaker, Michael"'

1. When and when not to use optimal model averaging.

Author

Schomaker, Michael and Heumann, Christian

Subjects
CAUSAL models, MACHINE learning, CONFIDENCE intervals, FORECASTING
Abstract

Traditionally model averaging has been viewed as an alternative to model selection with the ultimate goal to incorporate the uncertainty associated with the model selection process in standard errors and confidence intervals by using a weighted combination of candidate models. In recent years, a new class of model averaging estimators has emerged in the literature, suggesting to combine models such that the squared risk, or other risk functions, are minimized. We argue that, contrary to popular belief, these estimators do not necessarily address the challenges induced by model selection uncertainty, but should be regarded as attractive complements for the machine learning and forecasting literature, as well as tools to identify causal parameters. We illustrate our point by means of several targeted simulation studies. [ABSTRACT FROM AUTHOR]

Published
2020
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2. BackMatter.

Author

Heumann, Christian, Schomaker, Michael, and Shalabh

Published
2016

14. FrontMatter.

Author

Heumann, Christian, Schomaker, Michael, and Shalabh

Published
2016

15. Is the fetoplacental ratio a differential marker of fetal growth restriction in small for gestational age infants?

Author

Luque-Fernandez, Miguel, Ananth, Cande, Jaddoe, Vincent, Gaillard, Romy, Albert, Paul, Schomaker, Michael, McElduff, Patrick, Enquobahrie, Daniel, Gelaye, Bizu, and Williams, Michelle

Subjects
FETAL growth retardation, GESTATIONAL age, PLACENTA, BIRTH weight, BIOMARKERS, HYPOXEMIA, NECROSIS
Abstract

Higher placental weight relative to birthweight has been described as an adaptive mechanism to fetal hypoxia in small for gestational age (SGA) infants. However, placental weight alone may not be a good marker reflecting intrauterine growth restriction. We hypothesized that fetoplacental ratio (FPR)-the ratio between birthweight and placental weight-may serve as a good marker of SGA after adjustment for surrogates of fetal hypoxemia (maternal iron deficiency anemia, smoking and choriodecidual necrosis). We conducted a within-sibling analysis using data from the US National Collaborative Perinatal Project (1959-1966) of 1,803 women who delivered their first two (or more) consecutive infants at term (n = 3,494). We used variance-component fixed-effect linear regression models to explore the effect of observed time-varying factors on placental weight and conditional logistic regression to estimate the effects of the tertiles of FPRs (1st small, 2nd normal and 3rd large) on the odds of SGA infants. We found placental weights to be 15 g [95 % confidence interval (CI) 8, 23] higher and −7 g (95 % CI −13, −2) lower among women that had anemia and choriodecidual necrosis, respectively. After multivariable adjustment, newborns with a small FPR (1st-tertile ≤7) had twofold higher odds of being SGA (OR 2.0, 95 % CI 1.2, 3.5) than their siblings with a large FPR (3nd-tertile ≥9). A small FPR was associated with higher odds of SGA, suggesting that small FPR may serve as an indicator suggestive of adverse intrauterine environment. This observation may help to distinguish pathological from constitutional SGA. [ABSTRACT FROM AUTHOR]

Published
2015
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16. FrontMatter.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Published
2009

17. Datenanalyse.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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18. Lineare Regression.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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19. Grundlagen.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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20. Häufigkeitsverteilungen.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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21. Analyse des Zusammenhangs zweier Merkmale.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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22. Maβzahlen für eindimensionale Merkmale.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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23. Kombinatorik.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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24. BackMatter.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Published
2009

25. Elemente der Wahrscheinlichkeitsrechnung.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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26. Zufallsvariablen.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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27. Diskrete und stetige Standardverteilungen.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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28. Schätzung von Parametern.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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29. Prüfen statistischer Hypothesen.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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30. Nichtparametrische Tests.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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31. Multiple lineare Regression.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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32. Analyse von Kontingenztafeln.

Author

Toutenburg, Helge, Schomaker, Michael, Wiβmann, Malte, and Heumann, Christian

Abstract

Copyright of Arbeitsbuch Zur Deskriptiven und Induktiven Statistik (9783540890355) is the property of Springer Nature / Books and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2009
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48. Unemployment and stillbirth risk among foreign-born and Spanish pregnant women in Spain, 2007–2010: a multilevel analysis study.

Author

Luque-Fernandez, Miguel Angel, Franco, Manuel, Gelaye, Bizu, Schomaker, Michael, Garitano, Ignacio Gutierrez, D’Este, Catherine, and Williams, Michelle A.

Subjects
STILLBIRTH, UNEMPLOYMENT, PREGNANT women, SOCIOECONOMICS, IMMIGRANTS, EPIDEMIOLOGY
Abstract

We describe stillbirth and unemployment rates by autonomous region in Spain and analyse whether women who gave birth in regions with high unemployment rates were more likely to have a stillborn. We designed a multilevel population-based observational study of births from 2007 to 2010. We defined stillbirth as the outcome, individual maternal socioeconomic and pregnancy-related characteristics as covariates, and maternal autonomous region of residence as the contextual covariate. We used mixed-logistic regression models to account for differences across regions. In total, 1,920,235 singleton births and 5,560 stillbirths were included in the study. Women residing in autonomous regions with the highest rates of unemployment had a two-times-greater chance of delivering a stillborn (adjusted OR 2.60; 95 % CI 2.08–3.21). The region where women resided explained 14 % of the total individual differences in the risk of delivering a stillborn. The odds of stillbirth were 1.82 (95 % CI 1.62–2.05) times higher for African-born women than for Spanish-born women and 1.90 (95 % CI 1.68–2.15) times higher for women with low educational attainment than for women with higher education. In conclusion, regional disparities in stillbirth rates in Spain in the period 2007–2010 were mainly associated with mothers who had low levels of education, were African-born, and lived in regions with higher unemployment. [ABSTRACT FROM AUTHOR]

Published
2013
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49. Shrinkage averaging estimation.

Author

Schomaker, Michael

Subjects
ESTIMATION theory, MONTE Carlo method, LEAST squares, STOCHASTIC processes, GAMES of chance
Abstract

We discuss the impact of tuning parameter selection uncertainty in the context of shrinkage estimation and propose a methodology to account for problems arising from this issue: Transferring established concepts from model averaging to shrinkage estimation yields the concept of shrinkage averaging estimation (SAE) which reflects the idea of using weighted combinations of shrinkage estimators with different tuning parameters to improve overall stability, predictive performance and standard errors of shrinkage estimators. Two distinct approaches for an appropriate weight choice, both of which are inspired by concepts from the recent literature of model averaging, are presented: The first approach relates to an optimal weight choice with regard to the predictive performance of the final weighted estimator and its implementation can be realized via quadratic programming. The second approach has a fairly different motivation and considers the construction of weights via a resampling experiment. Focusing on Ridge, Lasso and Random Lasso estimators, the properties of the proposed shrinkage averaging estimators resulting from these strategies are explored by means of Monte-Carlo studies and are compared to traditional approaches where the tuning parameter is simply selected via cross validation criteria. The results show that the proposed SAE methodology can improve an estimators' overall performance and reveal and incorporate tuning parameter uncertainty. As an illustration, selected methods are applied to some recent data from a study on leadership behavior in life science companies. [ABSTRACT FROM AUTHOR]

Published
2012
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