Regression with fractional polynomials when interactions are erroneously omitted

2012 ◽  
Vol 142 (6) ◽  
pp. 1348-1355 ◽  
Author(s):  
Juxin Liu ◽  
Paul Gustafson
2015 ◽  
Vol 18 (4) ◽  
pp. 738-760 ◽  
Author(s):  
Ralitza Nikolaeva ◽  
Amit Bhatnagar ◽  
Sanjoy Ghose

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Andreas Heinecke ◽  
Marta Tallarita ◽  
Maria De Iorio

Abstract Background Network meta-analysis (NMA) provides a powerful tool for the simultaneous evaluation of multiple treatments by combining evidence from different studies, allowing for direct and indirect comparisons between treatments. In recent years, NMA is becoming increasingly popular in the medical literature and underlying statistical methodologies are evolving both in the frequentist and Bayesian framework. Traditional NMA models are often based on the comparison of two treatment arms per study. These individual studies may measure outcomes at multiple time points that are not necessarily homogeneous across studies. Methods In this article we present a Bayesian model based on B-splines for the simultaneous analysis of outcomes across time points, that allows for indirect comparison of treatments across different longitudinal studies. Results We illustrate the proposed approach in simulations as well as on real data examples available in the literature and compare it with a model based on P-splines and one based on fractional polynomials, showing that our approach is flexible and overcomes the limitations of the latter. Conclusions The proposed approach is computationally efficient and able to accommodate a large class of temporal treatment effect patterns, allowing for direct and indirect comparisons of widely varying shapes of longitudinal profiles.


Risk Analysis ◽  
2008 ◽  
Vol 28 (4) ◽  
pp. 891-905 ◽  
Author(s):  
Harriet Namata ◽  
Marc Aerts ◽  
Christel Faes ◽  
Peter Teunis

Author(s):  
Patrick Royston

Since Royston and Altman's 1994 publication ( Journal of the Royal Statistical Society, Series C 43: 429–467), fractional polynomials have steadily gained popularity as a tool for flexible parametric modeling of regression relationships. In this article, I present fp_select, a postestimation tool for fp that allows the user to select a parsimonious fractional polynomial model according to a closed test procedure called the fractional polynomial selection procedure or function selection procedure. I also give a brief introduction to fractional polynomial models and provide examples of using fp and fp_select to select such models with real data.


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