Internal and external validation of predictive models: A simulation study of bias and precision in small samples

2003 ◽  
Vol 56 (5) ◽  
pp. 441-447 ◽  
Author(s):  
Ewout W Steyerberg ◽  
Sacha E Bleeker ◽  
Henriëtte A Moll ◽  
Diederick E Grobbee ◽  
Karel G.M Moons
Methodology ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Jochen Ranger ◽  
Jörg-Tobias Kuhn

In this manuscript, a new approach to the analysis of person fit is presented that is based on the information matrix test of White (1982) . This test can be interpreted as a test of trait stability during the measurement situation. The test follows approximately a χ2-distribution. In small samples, the approximation can be improved by a higher-order expansion. The performance of the test is explored in a simulation study. This simulation study suggests that the test adheres to the nominal Type-I error rate well, although it tends to be conservative in very short scales. The power of the test is compared to the power of four alternative tests of person fit. This comparison corroborates that the power of the information matrix test is similar to the power of the alternative tests. Advantages and areas of application of the information matrix test are discussed.


Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1647
Author(s):  
Anna Kaczmarek ◽  
Małgorzata Muzolf-Panek

The aim of the study was to develop predictive models of thiol group (SH) level changes in minced raw and heat-treated chicken meat enriched with selected plant extracts (allspice, basil, bay leaf, black seed, cardamom, caraway, cloves, garlic, nutmeg, onion, oregano, rosemary, and thyme) during storage at different temperatures. Meat samples with extract addition were stored under various temperatures (4, 8, 12, 16, and 20 °C). SH changes were measured spectrophotometrically using Ellman’s reagent. Samples stored at 12 °C were used as the external validation dataset. SH content decreased with storage time and temperature. The dependence of SH changes on temperature was adequately modeled by the Arrhenius equation with average high R2 coefficients for raw meat (R2 = 0.951) and heat-treated meat (R2 = 0.968). Kinetic models and artificial neural networks (ANNs) were used to build the predictive models of thiol group decay during meat storage. The obtained results demonstrate that both kinetic Arrhenius (R2 = 0.853 and 0.872 for raw and cooked meat, respectively) and ANN (R2 = 0.803) models can predict thiol group changes in raw and cooked ground chicken meat during storage.


2020 ◽  
Vol 47 (9) ◽  
pp. 4125-4136
Author(s):  
Noemi Garau ◽  
Chiara Paganelli ◽  
Paul Summers ◽  
Wookjin Choi ◽  
Sadegh Alam ◽  
...  

2021 ◽  
Author(s):  
Jonathan Hsijing Lu ◽  
Alison Callahan ◽  
Birju Patel ◽  
Keith Morse ◽  
Dev Dash ◽  
...  

Objective: To assess whether the documentation available for commonly used machine learning models developed by an electronic health record (EHR) vendor provides information requested by model reporting guidelines. Materials and Methods: We identified items requested for reporting from model reporting guidelines published in computer science, biomedical informatics, and clinical journals, and merged similar items into representative "atoms". Four independent reviewers and one adjudicator assessed the degree to which model documentation for 12 models developed by Epic Systems reported the details requested in each atom. We present summary statistics of consensus, interrater agreement, and reporting rates of all atoms for the 12 models. Results: We identified 220 unique atoms across 15 model reporting guidelines. After examining the documentation for the 12 most commonly used Epic models, the independent reviewers had an interrater agreement of 76%. After adjudication, the model documentations' median completion rate of applicable atoms was 39% (range: 31%-47%). Most of the commonly requested atoms had reporting rates of 90% or above, including atoms concerning outcome definition, preprocessing, AUROC, internal validation and intended clinical use. For individual reporting guidelines, the median adherence rate for an entire guideline was 54% (range: 15%-71%). Atoms reported half the time or less included those relating to fairness (summary statistics and subgroup analyses, including for age, race/ethnicity, or sex), usefulness (net benefit, prediction time, warnings on out-of-scope use and when to stop use), and transparency (model coefficients). Atoms reported the least often related to missingness (missing data statistics, missingness strategy), validation (calibration plot, external validation), and monitoring (how models are updated/tuned, prediction monitoring). Conclusion: There are many recommendations about what should be reported about predictive models used to guide care. Existing model documentation examined in this study provides less than half of applicable atoms, and entire reporting guidelines have low adherence rates. Half or less of the reviewed documentation reported information related to usefulness, reliability, transparency and fairness of models. There is a need for better operationalization of reporting recommendations for predictive models in healthcare.


Author(s):  
N López‐Jiménez ◽  
F García‐Sánchez ◽  
R Hernández‐Pailos ◽  
V Rodrigo‐Álvaro ◽  
A Pascual‐Pedreño ◽  
...  

2020 ◽  
Author(s):  
Weelic Chong ◽  
Yang Hai ◽  
Jian Zhou ◽  
Lun-xu Liu

AbstractBackgroundAccurate clinical nodal staging of non-small cell lung cancer (NSCLC) is essential for surgical management. Some clinical node negative cases diagnosed preoperatively by CT were later staged as pathological N1 (pN1) or pN2. Our study aimed to evaluate factors related to pathological nodal upstaging and develop statistical models for predicting upstaging.MethodsWe retrospectively reviewed 1,735 patients with clinical node negative NSCLC from 2011 to 2016 in the West China Lung Cancer database. Demographic and clinical data were analyzed via univariate and multivariate approaches. Predictive models were developed on a training set and validated with independent datasets.Results171 (9.9%) clinical node negative patients have pathologic nodal upstaging to pN1. 191(11.0%) patients were upstaged to p(N1+N2). 91(5.2%) patients have pSN2 pathologic nodal upstaging. Preoperative factors were used to establish 3 statistical models for predicting pathological nodal upstaging. The area under the receiver operator characteristic (AUC) were 0.815, 0.768, and 0.726, for pN1, p(N1+N2) and pSN2 respectively.ConclusionOur models may help evaluate the possibility of nodal upstaging for clinical node negative NSCLC and enable surgeons to form appropriate plans preoperatively. External validation in a prospective multi-site study is needed before adoption into clinical practice.


2014 ◽  
Vol 85 (12) ◽  
pp. 892-899 ◽  
Author(s):  
Rafał Moszyński ◽  
Patryk Zywica ◽  
Andrzej Wojtowicz ◽  
Sebastian Szubert ◽  
Stefan Sajdak ◽  
...  

2017 ◽  
Vol 68 (2) ◽  
pp. 195 ◽  
Author(s):  
J. A. Cayuela

The regulation of The European Union for olive oil and olive pomace established the limit of 35 mg·kg-1 for fatty acids ethyl ester contents in extra virgin olive oils, from grinding seasons after 2016. In this work, predictive models have been established for measuring fatty acid ethyl and methyl esters and to measure the total fatty acid alkyl esters based on near infrared spectroscopy (NIRS), and used successfully for this purpose. The correlation coefficients from the external validation exercises carried out with these predictive models ranged from 0.84 to 0.91. Different classification tests using the same models for the thresholds 35 mg·kg-1 for fatty acid ethyl esters and 75 mg·kg-1 for fatty acid alkyl esters provided success percentages from 75.0% to 95.2%.


Sign in / Sign up

Export Citation Format

Share Document