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Biometrical Journal. Biometrische Zeitschrift

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https://www.readbyqxmd.com/read/28626952/multivariate-binary-classification-of-imbalanced-datasets-a-case-study-based-on-high-dimensional-multiplex-autoimmune-assay-data
#1
Laura Schlieker, Anna Telaar, Angelika Lueking, Peter Schulz-Knappe, Carmen Theek, Katja Ickstadt
The classification of a population by a specific trait is a major task in medicine, for example when in a diagnostic setting groups of patients with specific diseases are identified, but also when in predictive medicine a group of patients is classified into specific disease severity classes that might profit from different treatments. When the sizes of those subgroups become small, for example in rare diseases, imbalances between the classes are more the rule than the exception and make statistical classification problematic when the error rate of the minority class is high...
June 19, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28620935/fast-precision-estimation-in-high-dimensional-multivariate-joint-models
#2
Vahid Nassiri, Anna Ivanova, Geert Molenberghs, Geert Verbeke
A fast way is proposed based on the multiple outputation idea (Hoffman et al., ; Follmann et al., ) to calculate the precision of parameter estimates for high-dimensional multivariate joint models using a pairwise approach (Fieuws and Verbeke, ; Fieuws et al., ). Simulation results as well as data analysis shows possibly more than 2500 times faster computations using the proposed method. In our real data illustration, the time gain is more than 330 times.
June 16, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28605047/stratified-exact-tests-for-the-weak-causal-null-hypothesis-in-randomized-trials-with-a-binary-outcome
#3
Yasutaka Chiba
Fisher's exact test is commonly used to compare two groups when the outcome is binary in randomized trials. In the context of causal inference, this test explores the sharp causal null hypothesis (i.e. the causal effect of treatment is the same for all subjects), but not the weak causal null hypothesis (i.e. the causal risks are the same in the two groups). Therefore, in general, rejection of the null hypothesis by Fisher's exact test does not mean that the causal risk difference is not zero. Recently, Chiba (Journal of Biometrics and Biostatistics 2015; 6: 244) developed a new exact test for the weak causal null hypothesis when the outcome is binary in randomized trials; the new test is not based on any large sample theory and does not require any assumption...
June 12, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28593719/penalized-estimation-in-latent-markov-models-with-application-to-monitoring-serum-calcium-levels-in-end-stage-kidney-insufficiency
#4
Alessio Farcomeni
We introduce a penalized likelihood form for latent Markov models. We motivate its use for biomedical applications where the sample size is in the order of the tens, or at most hundreds, and there are only few repeated measures. The resulting estimates never break down, while spurious solutions are often obtained by maximizing the likelihood itself. We discuss model choice based on the Takeuchi Information Criterion. Simulations and a real-data application to monitoring serum Calcium levels in end-stage kidney disease are used for illustration...
June 8, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28547927/contribution-to-the-discussion-of-a-critical-evaluation-of-the-current-p-value-controversy
#5
Fulvio De Santis
No abstract text is available yet for this article.
May 26, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28547812/contribution-to-the-discussion-of-a-critical-evaluation-of-the-current-p-value-controversy
#6
Werner Brannath
No abstract text is available yet for this article.
May 26, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28543300/an-objective-bayes-perspective-on-p-values
#7
Leonhard Held
No abstract text is available yet for this article.
May 24, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28508545/comparison-of-joint-modeling-and-landmarking-for-dynamic-prediction-under-an-illness-death-model
#8
Krithika Suresh, Jeremy M G Taylor, Daniel E Spratt, Stephanie Daignault, Alexander Tsodikov
Dynamic prediction incorporates time-dependent marker information accrued during follow-up to improve personalized survival prediction probabilities. At any follow-up, or "landmark", time, the residual time distribution for an individual, conditional on their updated marker values, can be used to produce a dynamic prediction. To satisfy a consistency condition that links dynamic predictions at different time points, the residual time distribution must follow from a prediction function that models the joint distribution of the marker process and time to failure, such as a joint model...
May 16, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28508431/a-spatially-balanced-design-with-probability-function-proportional-to-the-within-sample-distance
#9
Roberto Benedetti, Federica Piersimoni
The units observed in a biological, agricultural, and environmental survey are often randomly selected from a finite population whose main feature is to be geo-referenced thus its spatial distribution should be used as essential information in designing the sample. In particular our interest is focused on probability samples that are well spread over the population in every dimension which in recent literature are defined as spatially balanced samples. To approach the problem we used the within sample distance as the summary index of the spatial distribution of a random selection criterion...
May 16, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28504870/a-critical-evaluation-of-the-current-p-value-controversy
#10
REVIEW
Stefan Wellek
This article has been triggered by the initiative launched in March 2016 by the Board of Directors of the American Statistical Association (ASA) to counteract the current p-value focus of statistical research practices that allegedly "have contributed to a reproducibility crisis in science." It is pointed out that in the very wide field of statistics applied to medicine, many of the problems raised in the ASA statement are not as severe as in the areas the authors may have primarily in mind, although several of them are well-known experts in biostatistics and epidemiology...
May 15, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28503762/contribution-to-the-discussion-of-a-critical-evaluation-of-the-current-p-value-controversy
#11
Mauro Gasparini
No abstract text is available yet for this article.
May 15, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28480583/editorial-for-the-special-topic-on-multiple-comparison-procedures
#12
Ajit C Tamhane
No abstract text is available yet for this article.
May 8, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28471053/contribution-to-the-discussion-of-the-paper-by-stefan-wellek-a-critical-evaluation-of-the-current-p-value-controversy
#13
Alessio Farcomeni
No abstract text is available yet for this article.
May 4, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28464322/comparing-dependent-kappa-coefficients-obtained-on-multilevel-data
#14
Sophie Vanbelle
Reliability and agreement are two notions of paramount importance in medical and behavioral sciences. They provide information about the quality of the measurements. When the scale is categorical, reliability and agreement can be quantified through different kappa coefficients. The present paper provides two simple alternatives to more advanced modeling techniques, which are not always adequate in case of a very limited number of subjects, when comparing several dependent kappa coefficients obtained on multilevel data...
May 2, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28464317/joint-analysis-of-longitudinal-and-survival-aids-data-with-a-spatial-fraction-of-long-term-survivors-a-bayesian-approach
#15
Rui Martins, Giovani L Silva, Valeska Andreozzi
A typical survival analysis with time-dependent covariates usually does not take into account the possible random fluctuations or the contamination by measurement errors of the variables. Ignoring these sources of randomness may cause bias in the estimates of the model parameters. One possible way for overcoming that limitation is to consider a longitudinal model for the time-varying covariates jointly with a survival model for the time to the event of interest, thereby taking advantage of the complementary information flowing between these two-model outcomes...
May 2, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28452192/contribution-to-the-discussion-of-a-critical-evaluation-of-the-current-p-value-controversy
#16
Stephen Senn
I pick up a very few points of minor disagreement with Stefan Wellek's comprehensive review of P-values in this journal. I conclude that P-values have a limited function in statistical inference but can nevertheless have their uses.
April 27, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28440065/contribution-to-the-discussion-of-a-critical-evaluation-of-the-current-p-value-controversy
#17
Jelle J Goeman
No abstract text is available yet for this article.
April 25, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28436123/an-improved-uniformly-more-powerful-exact-fisher-hayter-pairwise-comparisons-procedure
#18
Bushi Wang, Xinping Cui
Pairwise comparison is a very common multiple comparison problem. It is known that Fisher's LSD test does not control the familywise error rate (FWER) when there are more than three groups to be compared. Improved testing strategies include the Tukey-Kramer (TK) test that eliminates the F-test step and the two-step Fisher-Hayter (FH) test which requires a significant F-test. We propose a modified FH-test that is uniformly more powerful than the original version and relies on exact size α test under the balanced model...
April 24, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28436113/using-predictions-from-a-joint-model-for-longitudinal-and-survival-data-to-inform-the-optimal-time-of-intervention-in-an-abdominal-aortic-aneurysm-screening-programme
#19
Michael J Sweeting
Joint models of longitudinal and survival data can be used to predict the risk of a future event occurring based on the evolution of an endogenous biomarker measured repeatedly over time. This has led naturally to the use of dynamic predictions that update each time a new longitudinal measurement is provided. In this paper, we show how such predictions can be utilised within a fuller decision modelling framework, in particular to allow planning of future interventions for patients under a 'watchful waiting' care pathway...
April 24, 2017: Biometrical Journal. Biometrische Zeitschrift
https://www.readbyqxmd.com/read/28436052/clustering-multiply-imputed-multivariate-high-dimensional-longitudinal-profiles
#20
Liesbeth Bruckers, Geert Molenberghs, Paul Dendale
In this paper, we propose a method to cluster multivariate functional data with missing observations. Analysis of functional data often encompasses dimension reduction techniques such as principal component analysis (PCA). These techniques require complete data matrices. In this paper, the data are completed by means of multiple imputation, and subsequently each imputed data set is submitted to a cluster procedure. The final partition of the data, summarizing the partitions obtained for the imputed data sets, is obtained by means of ensemble clustering...
April 24, 2017: Biometrical Journal. Biometrische Zeitschrift
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