Search results for "Internal validation"

Speeding up the Consensus Clustering methodology for microarray data analysis

2010

Abstract Background The inference of the number of clusters in a dataset, a fundamental problem in Statistics, Data Analysis and Classification, is usually addressed via internal validation measures. The stated problem is quite difficult, in particular for microarrays, since the inferred prediction must be sensible enough to capture the inherent biological structure in a dataset, e.g., functionally related genes. Despite the rich literature present in that area, the identification of an internal validation measure that is both fast and precise has proved to be elusive. In order to partially fill this gap, we propose a speed-up of Consensus (Consensus Clustering), a methodology whose purpose…

Predicting survival after transarterial chemoembolization for hepatocellular carcinoma using a neural network: A Pilot Study.

2019

BACKGROUND AND AIMS Deciding when to repeat and when to stop transarterial chemoembolization (TACE) in patients with hepatocellular carcinoma (HCC) can be difficult even for experienced investigators. Our aim was to develop a survival prediction model for such patients undergoing TACE using novel machine learning algorithms and to compare it to conventional prediction scores, ART, ABCR and SNACOR. METHODS For this retrospective analysis, 282 patients who underwent TACE for HCC at our tertiary referral centre between January 2005 and December 2017 were included in the final analysis. We built an artificial neural network (ANN) including all parameters used by the aforementioned risk scores a…

A Comparison of Formulae for Calculating Cost-Efficient Sample Sizes of Case-Control Studies with an Internal Validation Scheme

2000

When a case-control study is planned to include an internal validation study, the sample size of the study and the proportion of validated observations has to be calculated. There are a variety of alternative methods to accomplish this. In this article some possible procedures will be compared in order to clarify whether considerable differences in the suggested optimal designs occur, dependent on the used method.

Automatic classification of acoustically detected krill aggregations: A case study from Southern Ocean

2022

Acoustic surveys represent the standard methodology to assess the spatial distribution and abundance of pelagic organisms characterized by aggregative behaviour. The species identification of acoustically observed aggregations is usually performed by taking into account the biological sampling and according to expert-based knowledge. The precision of survey estimates, such as total abundance and spatial distribution, strongly depends on the efficiency of acoustic and biological sampling as well as on the species identification. In this context, the automatic identification of specific groups based on energetic and morphological features could improve the species identification process, allo…

Derivation and validation of a novel bleeding risk score for elderly patients with venous thromboembolism on extended anticoagulation

2017

SummaryExisting clinical scores do not perform well in predicting bleeding in elderly patients with acute venous thromboembolism (VTE). We sought to derive an easy-to-use clinical score to help physicians identify elderly patients with VTE who are at high-risk of bleeding during extended anticoagulation (>3 months). Our derivation sample included 743 patients aged ≥65 years with VTE who were enrolled in a prospective multicenter cohort study. All patients received extended anticoagulation with vitamin K antagonists. We derived our score using competing risk regression, with the time to a first major bleeding up to 36 months of extended anticoagulation as the outcome, and 17 candidate var…

Application of Molecular Topology to the Prediction of Water Quality Indices of Alkylphenol Pollutants

2011

In this paper, topological-mathematical models based on multilineal regression analysis have been built as a model of the degradability of 26 alkylphenols through the Chemical Oxygen Demand (COD) and Biochemical Oxigen Demand (BOD5). Two models with three-variable were selected (r2= 0.8793 and q2=0.8075 for log(1/COD) and r2= 0.8928 and q2=0.8327 for log(1/BOD5). The models were validated by cross-validation, internal validation and randomization tests. The results, which stand in good accordance with the obtained results, confirm the robustness of the method.

Algorithms for internal validation clustering measures in the post genomic era.

2011

Features Associated with Recurrence Beyond 5 Years After Nephrectomy and Nephron-Sparing Surgery for Renal Cell Carcinoma: Development and Internal V…

2014

Background: Approximately 10-20% of recurrences in patients treated with nephrectomy for renal cell carcinoma (RCC) develop beyond 5 yr after surgery (late recurrence). Objective: To determine features associated with late recurrence. Design, setting, and participants: A total of 5009 patients from a multicenter database comprising 13 107 RCC patients treated surgically had a minimum recurrence-free survival of 60 mo (median follow-up [FU]: 105 mo [range: 78-135]); at last FU, 4699 were disease free (median FU: 103 mo [range: 78-134]), and 310 patients (6.2%) experienced disease recurrence (median FU: 120 mo [range: 93-149]). Interventions: Patients underwent radical nephrectomy or nephron-…