Analyzing coarsened categorical data with or without probabilistic information

In some applications, only a coarsened version of a categorical outcome variable can be observed. Parametric inference based on the maximum likelihood approach is feasible in principle, but it cannot be covered computationally by standard software tools. In this article, we present two commands facilitating maximum likelihood estimation in this situation for a wide range of parametric models for categorical outcomes-in the cases both of a nominal and an ordinal scale. In particular, the case of probabilistic information about the possible values of the outcome variable is also covered. Two examples motivating this scenario are presented and analyzed

Statistische Beratung zwischen Anspruch und Wirklichkeit

Im Rahmen der SoftStat'95 fand ein wissenschaftliches Symposium zum Thema Statistische Beratung statt. Vor diesem Symposium hatten auch die zwei Vorträge von G. Roussas (Principles and Practics of Statistical Consulting) und H. Riedwyl (Statistische Beratung - Gestern und Heute) dieses Thema zum Inhalt. Im Rahmen des Symposiums wurden von den beiden Organisatoren fünf Thesen formuliert, die dann anschließend von den beteiligten Diskutanten kommentiert wurden. Der Beitrag präsentiert auf der Basis eins Tonbandmitschnitts Diskussionsbeiträge zu folgenden Thesen: (1) 99 Prozent der Beratungsfälle kommen mit einem Prozent des Methodenspektrums der Softwareprodukte aus. (2) Die Anerkennung von Beratung als Teil einer wissenschaftlichen Tätigkeit fehlt. (3) Der Beratende sollte die Berechnungen, derentwegen er um eine Beratung gebeten wird, besser selber durchführen. (4) Statistische Programmpakete sind kontraproduktiv für die Beratung. (5) Statistische Programmpakete bieten keine Unterstützung für die Beratung. (ICE2

Assessing in vivo articular cartilage mechanosensitivity as outcome of high tibial osteotomy in patients with medial compartment osteoarthritis: experimental protocol

Objective To propose an experimental protocol for using high tibial osteotomy (HTO) as a model for studying in vivo biological effects of large permanent changes in ambulatory load. Design This study is a prospective multimodal (clinical, biomechanical, biological) data collection without randomization. The study will examine a cohort of 40 patients with medial compartment knee OA undergoing opening wedge HTO. Experimental protocol Before planned HTO, patients will be clinically assessed (including mechanical axis measurement from radiographs) and complete questionnaires on physical function. Patients will complete a walking stress test with blood sampling (30 min walking, 5.5 h sitting), and undergo gait analysis. Six weeks after HTO (at the time of full weight bearing), the mechanical axis will be measured from radiographs. Patients will complete the questionnaires and a walking stress test with blood sampling, and undergo gait analysis 6 months after HTO. The peak external knee adduction moment, knee external knee adduction moment impulse and peak external knee flexion moment will be used as surrogates of ambulatory load. Load-induced changes in cartilage biomarkers will be used as surrogates of metabolic changes in response to ambulatory load. At the 12-month follow-up, subjects will complete the questionnaires. Conclusion The results of this study can be considered as proof-of-concept of a potential diagnostic test (walking stress test) for cartilage degeneration and its prognostic value. A direct relationship between ambulatory load and cartilage metabolism assessed as degradation to synthesis ratio would allow developing novel load-modifying interventions and evaluating the efficacy of existing interventions

Cluster Analyses of a Target Data Set from the IFCS Cluster Benchmark Data Repository: Introduction to the Special Issue

After a brief introduction to benchmarking in data analysis in general and in cluster analysis in particular, we describe the setup of the IFCS Cluster Benchmark Data Repository along with two challenges connected with it. The first of these challenges called for data sets to be contributed to the repository; the second one pertained to cluster analyses of the winning data set of the first challenge. Subsequently, we introduce the winning data set of the first challenge together with relevant meta-data. We conclude with a brief description of the organization of the present special issue, which comprises reports of analyses that have been submitted as contributions to the second challenge

Abductor muscle strength deficit in patients after total hip arthroplasty for hip osteoarthritis: a protocol for a systematic review and meta-analysis

Conservation of abductor muscle strength is directly associated with physical function after total hip replacement (THA). Although many studies have tried to explore and quantify a potential abductor muscle strength deficit after THA as well as identify possible causes and treatment options, this topic has not been addressed systematically.; Human-based studies reporting measurements of hip abductor strength will be included in this review. Studies reporting on hip abductor strength measured manually or isometric measurements at an abduction angle other than 0° will not be considered. No restriction will be placed on study design, publication date operative approach, prosthesis design, age and sex of the patients or severity of OA. Data sources will be Embase via embase.com, Medline ALL via Ovid and the Cochrane Central Register of Controlled Trials. The preliminary search was conducted on 5 May 2019. Data regarding absolute values or torque ratio of hip abductor torque between sides as well as patient demographic data, surgical approaches and rehabilitation protocols will be extracted. The assessment of quality and risk of bias will be performed with the modified Newcastle-Ottawa Scale. The screening, data extraction and quality assessment will be performed by two reviewers independently. Where necessary, a third review author will make a final judgement. Narrative synthesis as well as tabular presentation of the extracted data will be included. Whenever possible, metaregression and subgroup specific meta-analyses will be used to investigate the influence of time since THA and type of measurement (isokinetic or isometric) on the different outcomes. In case of sufficient information, these analyses will be extended to include characteristics such as age, sex, surgical approach or rehabilitation programme.; No ethics approval is required. The results will be disseminated through peer-reviewed publications and conference presentations.; CRD42020153185

Age-at-death estimation in archaeological samples: Differences in population means resulting from different aging methods can be predicted from the mean ages of method-specific reference samples

Age mimicry is a well-known phenomenon in the application of osteological age-estimation methods. Age mimicry refers to the fact that predicting age-at-death from a specific trait (age indicator) based on the relation observed in a specific reference sample implies that age estimates to some degree reflect the age structure of the reference sample. In particular, the estimated population mean in a target population in which an age-estimation method is applied is shifted towards the mean in the method-specific reference sample. Consequently, differences in population means between different age-estimation methods in the same target population may be due to differences in mean age of the reference samples used to develop the age-estimation methods. We aim at quantifying the expected magnitude for such differences. Fifteen different traditional age-estimation methods were applied to a sample of 675 adult individuals from the early medieval cemetery of Mannheim-Seckenheim. The relation of the observed estimated population age means and the mean age in the reference samples was analyzed by linear regression. We find that up to 80% of the variation in the estimated population age means can be explained by the variation of the mean age in the reference samples. Furthermore, differences in the magnitude of 3 to 4 years in the mean age between two reference samples can imply a 1-year difference in estimated target population age means. Because large differences in mean age between reference samples used to develop different age-estimation methods are common, some care is needed in interpreting differences between individual age estimates or population mean age estimates in cases where different age-estimation techniques are used

INDIVIDUELLE FORSKELLE I DANSKE BØRNS TIDLIGE SPROGTILEGNELSE - Hvad kan børne- og forældrerelaterede baggrundsfaktorer forklare?

Baseret på et tværsnitligt forældrerapportstudie af 6.112 danske børn i alderen 8-36 måneder præsenterer artiklen analyser af tilegnelsen af nogle centrale sproglige dimensioner. Analyserne viser, at langsomme og hurtige børn når milepælene i den samme rækkefølge, men at der er meget stor tidsmæssig spredning blandt børnene. Dernæst vises analyser af sammenhængen mellem faktorerne køn, antal søskende, dagtilbud, forældres uddannelse og beskæftigelse samt omfang af højtlæsning/sang og børns tilegnelse af det receptive og produktive ordforråd mhp. at undersøge, om sådanne baggrundsvariable kan forklare de store individuelle forskelle blandt børn. Det var kun muligt at påvise direkte effekt af køn, højtlæsning/sang samt antal timer i dagtilbud, og samlet set kunne baggrundsfaktorerne kun forklare mellem 3.2-8.7% af variationen blandt børnene afhængigt af alder. Artiklen indledes og afrundes med en introduktion til og diskussion af international forskning på området

A Pooled Data Analysis from Three Research Labs

Paired associative stimulation (PAS) is a widely used transcranial magnetic stimulation (TMS) paradigm to non-invasively induce synaptic plasticity in the human brain in vivo. Altered PAS-induced plasticity has been demonstrated for several diseases. However, researchers are faced with a high inter- and intra- subject variability of the PAS response. Here, we pooled original data from nine PAS studies from three centers and analyzed the combined dataset of 190 healthy subjects with regard to age dependency, the role of stimulation parameters and the effect of different statistical methods. We observed no main effect of the PAS intervention over all studies (F(2;362) = 0.44; p = 0.644). The rate of subjects showing the expected increase of motor evoked potential (MEP) amplitudes was 53%. The PAS effect differed significantly between studies as shown by a significant interaction effect (F(16;362) = 1.77; p = 0.034) but post-hoc testing did not reveal significant effects after correction for multiple tests. There was a trend toward increased variability of the PAS effect in older subjects. Acquisition parameters differed across studies but without systematically influencing changes in MEP-size. The use of post/baseline quotients systematically indicated stronger PAS effects than post/baseline difference or the logarithm of the post/baseline quotient. The non-significant PAS effects across studies and a wide range of responder rates between studies indicate a high variability of this method. We were thus not able to replicate findings from a previous meta-analysis showing robust effects of PAS. No pattern emerged regarding acquisition parameters that at this point could guide future studies to reduce variability and help increase response rate. For future studies, we propose to report the responder rate and recommend the use of the logarithmized post/baseline quotient for further analyses to better address the possibility that results are driven by few extreme cases