@article{SchmidtBrunnerPreckel2018,
  author    = {Schmidt, Isabelle and Brunner, Martin and Preckel, Franzis},
  title     = {Effects of achievement differences for internal/external frame of reference model investigations},
  series = {British journal of educational psychology},
  volume    = {88},
  journal   = {British journal of educational psychology},
  number    = {4},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0007-0998},
  doi       = {10.1111/bjep.12198},
  pages     = {513 -- 528},
  year      = {2018},
  abstract  = {Background Achievement in math and achievement in verbal school subjects are more strongly correlated than the respective academic self-concepts. The internal/external frame of reference model (I/E model; Marsh, 1986, Am. Educ. Res. J., 23, 129) explains this finding by social and dimensional comparison processes. We investigated a key assumption of the model that dimensional comparisons mainly depend on the difference in achievement between subjects. We compared correlations between subject-specific self-concepts of groups of elementary and secondary school students with or without achievement differences in the respective subjects. Aims The main goals were (1) to show that effects of dimensional comparisons depend to a large degree on the existence of achievement differences between subjects, (2) to demonstrate the generalizability of findings over different grade levels and self-concept scales, and (3) to test a rarely used correlation comparison approach (CCA) for the investigation of I/E model assumptions. Samples We analysed eight German elementary and secondary school student samples (grades 3-8) from three independent studies (Ns 326-878). Method Correlations between math and German self-concepts of students with identical grades in the respective subjects were compared with the correlation of self-concepts of students having different grades using Fisher's Z test for independent samples. Results In all samples, correlations between math self-concept and German self-concept were higher for students having identical grades than for students having different grades. Differences in median correlations had small effect sizes for elementary school students and moderate effect sizes for secondary school students. Conclusions Findings generalized over grades and indicated a developmental aspect in self-concept formation. The CCA complements investigations within I/E-research.},
  language  = {en}
}
@misc{SachseBillaultBowenetal.2012,
  author    = {Sachse, Dirk and Billault, Isabelle and Bowen, Gabriel J. and Chikaraishi, Yoshito and Dawson, Todd E. and Feakins, Sarah J. and Freeman, Katherine H. and Magill, Clayton R. and McInerney, Francesca A. and van der Meer, Marcel T. J. and Polissar, Pratigya and Robins, Richard J. and Sachs, Julian P. and Schmidt, Hanns-Ludwig and Sessions, Alex L. and White, James W. C. and West, Jason B. and Kahmen, Ansgar},
  title     = {Molecular Paleohydrology interpreting the Hydrogen- Isotopic Composition of Lipid Biomarkers from Photosynthesizing Organisms},
  series = {Annual review of earth and planetary sciences},
  volume    = {40},
  journal   = {Annual review of earth and planetary sciences},
  number    = {1},
  editor    = {Jeanloz, R},
  publisher = {Annual Reviews},
  address   = {Palo Alto},
  isbn      = {978-0-8243-2040-9},
  issn      = {0084-6597},
  doi       = {10.1146/annurev-earth-042711-105535},
  pages     = {221 -- 249},
  year      = {2012},
  abstract  = {Hydrogen-isotopic abundances of lipid biomarkers are emerging as important proxies in the study of ancient environments and ecosystems. A decade ago, pioneering studies made use of new analytical methods and demonstrated that the hydrogen-isotopic composition of individual lipids from aquatic and terrestrial organisms can be related to the composition of their growth (i.e., environmental) water. Subsequently, compound-specific deuterium/hydrogen (D/H) ratios of sedimentary biomarkers have been increasingly used as paleohydrological proxies over a range of geological timescales. Isotopic fractionation observed between hydrogen in environmental water and hydrogen in lipids, however, is sensitive to biochemical, physiological, and environmental influences on the composition of hydrogen available for biosynthesis in cells. Here we review the factors and processes that are known to influence the hydrogen-isotopic compositions of lipids-especially n-alkanes-from photosynthesizing organisms, and we provide a framework for interpreting their D/H ratios from ancient sediments and identify future research opportunities.},
  language  = {en}
}
@article{SchmidtBrunnerKelleretal.2017,
  author    = {Schmidt, Isabelle and Brunner, Martin and Keller, Lena and Scherrer, Vsevolod and Wollschlager, Rachel and Baudson, Tanja Gabriele and Preckel, Franzis},
  title     = {Profile formation of academic self-concept in elementary school students in grades 1 to 4},
  series = {PLoS one},
  volume    = {12},
  journal   = {PLoS one},
  publisher = {PLoS},
  address   = {San Fransisco},
  issn      = {1932-6203},
  doi       = {10.1371/journal.pone.0177854},
  pages     = {27},
  year      = {2017},
  language  = {en}
}