The expansion of a Simex estimator in the nonlinear errors-in-variables model with small measurement errors

The nonlinear structural errors-in-variables model is investigated. We consider a Simex estimator with polynomial extrapolation function. The expansion of a Simex estimator is based on the asymptotic expansion of a naive estimator for small measurement errors. It is shown that the Simex estimator has an asymptotic deviation from a true value of the unknown parameter which is negligible compared with a measurement error variance, while the deviation of the naive estimator is proportional to the measurement error variance

Haplotype Reconstruction Error as a Classical Misclassification Problem: Introducing Sensitivity and Specificity as Error Measures

BACKGROUND: Statistically reconstructing haplotypes from single nucleotide polymorphism (SNP) genotypes, can lead to falsely classified haplotypes. This can be an issue when interpreting haplotype association results or when selecting subjects with certain haplotypes for subsequent functional studies. It was our aim to quantify haplotype reconstruction error and to provide tools for it. METHODS AND RESULTS: By numerous simulation scenarios, we systematically investigated several error measures, including discrepancy, error rate, and R(2), and introduced the sensitivity and specificity to this context. We exemplified several measures in the KORA study, a large population-based study from Southern Germany. We find that the specificity is slightly reduced only for common haplotypes, while the sensitivity was decreased for some, but not all rare haplotypes. The overall error rate was generally increasing with increasing number of loci, increasing minor allele frequency of SNPs, decreasing correlation between the alleles and increasing ambiguity. CONCLUSIONS: We conclude that, with the analytical approach presented here, haplotype-specific error measures can be computed to gain insight into the haplotype uncertainty. This method provides the information, if a specific risk haplotype can be expected to be reconstructed with rather no or high misclassification and thus on the magnitude of expected bias in association estimates. We also illustrate that sensitivity and specificity separate two dimensions of the haplotype reconstruction error, which completely describe the misclassification matrix and thus provide the prerequisite for methods accounting for misclassification

Modelling data from inside the Earth: local smoothing of mean and dispersion structure in deep drill data

Kauermann G, Kuchenhoff H. Modelling data from inside the Earth: local smoothing of mean and dispersion structure in deep drill data. STATISTICAL MODELLING. 2003;3(1):43-64.The paper describes the analysis of data originating from the German Deep Drill Program. The amount of 'cataclastic rocks' is modelled with data resulting from a series of measurements taken from deep drill samples ranging from 1000 up to 5000 m depth. The measurements thereby describe the amount of strongly deformed rock particles and serve as indicator for the occurrence of cataclastic shear zones, which are areas of severely 'ground' stones due to movements of different layers in the earth crust. The data represent a 'depth series' as analogue to a 'time series', with mean, dispersion and correlation structure varying in depth. The general smooth structure is thereby disturbed by peaks and outliers so that robust procedures have to be applied for estimation. In terms of statistical modelling technology three different peculiarities of the data have to be tackled simultaneously, that is estimation of the correlation structure, local bandwidth selection and robust smoothing. To do so, existing routines are adapted and combined in new 'two-stage' estimation procedures

The uncertainty of psychological and psychiatric diagnoses

Psychiatric and psychological diagnoses are imperfect. Unlike somatic medicine, most psychological and psychiatric phenomena have no gold standard to establish their presence beyond reasonable doubt. Consequently, prevalence estimates are based on the average agreement of imperfect evaluators. Kuchenhoff, Augustin, and Kunz (2012) provided a statistical method for estimating confidence intervals of the prevalence based on the well-known kappa coefficient of interrater agreement. We expand this method and derive confidence intervals for the probability of a diagnosis being true (i.e., the positive predictive value). We illustrate the method and its results with empirical data for a particular type of paraphilia (pedophilia) in sexual offenders. The findings indicate that up to 1 in 3 diagnoses of pedophilia may be wrong. Given the similar rates of prevalence and interrater agreement reported for diagnoses in general psychiatry (such as schizophrenia or affective disorders), the results likely apply to other diagnostic domains as well. (PsycINFO Database Recor

Bovine somatic cell nuclear transfer using recipient oocytes recovered by ovum pick up. Effect of maternal lineage of oocyte donors.

The efficiency of bovine nuclear transfer using recipient oocytes recovered by ultrasound-guided follicle aspiration (ovum pick-up [OPU]) was investigated. Oocyte donors were selected from 2 distinct maternal lineages (A and B) differing in 11 nucleotide positions of the mitochondrial DNA control region. A total of 1342 cumulus-oocyte complexes (COCs) were recovered. The numbers of total COCs and class I/II COCs recovered from donors of lineage A were higher (P < 0.001) than those obtained from lineage B. Follicle aspiration once per week yielded a higher (P < 0.001) total number of COCs per session than aspiration twice per week, whereas the reproduction status of donors (heifer vs. cow) had no effect on OPU results. Of the 1342 oocytes recovered, 733 (55%) were successfully matured in vitro and used for nuclear transfer. Fusion was achieved in 550 (75%) karyoplast-cytoplast complexes (KCCs), resulting in 277 (50%) cleaved embryos on Day 3. On Day 7 of culture, 84 transferable embryos (15% based on fused KCCs) were obtained. After 38 transfers (10 single, 22 double, and 6 triple transfers), 9 recipients (8 double and 1 triple transfer) were diagnosed as pregnant on Day 28, corresponding to a pregnancy rate of 24%. The proportion of transferable embryos on Day 7 was significantly (P < 0.05) influenced by maternal lineage of oocyte donors and by the frequency of follicle aspiration. Our study demonstrates the feasibility of generating nuclear transfer embryos with defined cytoplasmic background. These will be valuable tools to experimentally dissect the effects of nuclear and cytoplasmic components on embryonic, fetal, and postnatal development.Katja Brüggerhoff, Valeri Zakhartchenko, Hendrik Wenigerkind, Horst-Dieter Reichenbach, Katja Prelle, Wolfgang Schernthaner, Ramiro Alberio, Helmut Küchenhoff, Miodrag Stojkovic, Gottfried Brem, Stefan Hiendleder, and Eckhard Wol