Oliveira, Thiago P. and de Andrade Moral, Rafael and Zocchi, Silvio S. and Demetrio, Clarice G. B. and Hinde, John (2020) lcc: an R package to estimate the concordance correlation, Pearson correlation and accuracy over time. PeerJ. pp. 1-29. ISSN 2167-8359

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Abstract

Background and Objective: Observational studies and experiments in medicine, pharmacology and agronomy are often concerned with assessing whether different methods/raters produce similar values over the time when measuring a quantitative variable. This article aims to describe the statistical package lcc, for are, that can be used to estimate the extent of agreement between two (or more) methods over the time, and illustrate the developed methodology using three real examples. Methods: The longitudinal concordance correlation, longitudinal Pearson correlation, and longitudinal accuracy functions can be estimated based on fixed effects and variance components of the mixed-effects regression model. Inference is made through bootstrap confidence intervals and diagnostic can be done via plots, and statistical tests. Results: The main features of the package are estimation and inference about the extent of agreement using numerical and graphical summaries. Moreover, our approach accommodates both balanced and unbalanced experimental designs or observational studies, and allows for different within-group error structures, while allowing for the inclusion of covariates in the linear predictor to control systematic variations in the response. All examples show that our methodology is flexible and can be applied to many different data types. Conclusions: The lcc package, available on the CRAN repository, proved to be a useful tool to describe the agreement between two or more methods over time, allowing the detection of changes in the extent of agreement. The inclusion of different structures for the variance-covariance matrices of random effects and residuals makes the package flexible for working with different types of databases.

Item Type:	Article
Additional Information:	Licence This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ) and either DOI or URL of the article must be cited. Cite this article Oliveira TP, Moral RA, Zocchi SS, Demetrio CGB, Hinde J. 2020. lcc: an R package to estimate the concordance correlation, Pearson correlation and accuracy over time. PeerJ 8:e9850 https://doi.org/10.7717/peerj.9850
Keywords:	Bootstrap procedures; Extent of agreement; Heteroscedasticity; Polynomial mixed-effects regression model; Longitudinal data; Precision; Accuracy;
Academic Unit:	Faculty of Science and Engineering > Mathematics and Statistics
Item ID:	14608
Identification Number:	https://doi.org/10.7717/peerj.9850
Depositing User:	Rafael de Andrade Moral
Date Deposited:	19 Jul 2021 14:56
Journal or Publication Title:	PeerJ
Publisher:	PeerJ
Refereed:	Yes
URI:	Publisher
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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