PubMed Health⌕ Search

PubMed · 11307859

Combining regression trees and radial basis function networks.

Abstract

We describe a method for non-parametric regression which combines regression trees with radial basis function networks. The method is similar to that of Kubat, who was first to suggest such a combination, but has some significant improvements. We demonstrate the features of the new method, compare its performance with other methods on DELVE data sets and apply it to a real world problem involving the classification of soybean plants from digital images.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Orr, J Hallam, K Takezawa, A Murra, S Ninomiya, M Oide, T Leonard. 2000. Combining regression trees and radial basis function networks.. https://doi.org/10.1142/s0129065700000363

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Penalized Cumulative Probability Model for a Continuous Outcome Subject to Detection Limits.

Mixed-type outcome data occur when the outcome variable's distribution is a mixture of both continuous and discrete ordinal variables. Such mixed-type outcomes are common in biomedical, psychological, and the health sciences, particularly for variables having either a detection or quantitation limit. When interest lies in identifying a combination of genomic features associated with a mixed-type outcome, any method used would require a variable selection strategy for high-dimensional data. Unfortunately, few variable selection methods exist for modeling a mixed-type outcome when the covariate space is high dimensional. This study develops a high-dimensional penalized cumulative probability model (CPM), to allow for the identification of genomic features associated with mixed-type outcome of interest. We demonstrated how such model may be estimated using the iterative penalization procedure-the generalized monotone incremental forward stagewise (GMIFS) algorithm. The Model-X knockoffs procedure was combined with the estimation algorithm to control the false discovery rates (FDR) when performing variable selection. Through extensive simulation studies, our penalized CPM was shown to outperform alternative methods in terms of controlled variable selection performance by achieving high statistical power with the FDR being controlled at the target level. We demonstrate the utility of our method by applying it to predict estimated glomeruli filtration rate (eGFR) in kidney transplant recipients at 24 months post-transplant using baseline gene expression data as predictors. Our CPM model identified five genes associated with this mixed-type outcome which have important links to renal disease, which may provide prognostic guidance for kidney transplantation recipients.

Models, Statistical↗

Identification of critical process variables for coating actives onto tablets via statistically designed experiments.

The objective of this work was to identify, using a statistical experimental design, the critical processing variables that affect content uniformity and loading of active agent coated on tablets in a 24" Accela-Cota. United States Pharmacopeia (USP) specifies that the % relative standard deviation (RSD) of drug content within a batch should be less than 6%. A Plackett-Burman experimental design was used to identify the process variables that influence the content uniformity and loading efficiency of the drug in the aqueous-based film coat of the tablets. The process variables investigated were inlet airflow, pan speed, inlet air temperature, coating time, atomization pressure, and fan pressure. Atomization pressure was identified as a major variable with respect to content uniformity (P<0.01). Pan speed and coating duration were also identified as variables significantly affecting content uniformity (P<0.05). Fan pressure was identified as a critical variable affecting recovery (P<<0.01). Temperature also significantly affected recovery (P<0.05). A good correlation was obtained between observed and predicted values for content uniformity (r(2)=0.85) and recovery (r(2)=0.95). It was possible to achieve % RSD less than 6% while maintaining the recovery at 80% or higher.

Models, Statistical↗

Experimental verification of overdispersion in radioassay data.

New evidence is provided suggesting that radioassay data are frequently overdispersed with respect to the Poisson distribution. Twelve cases of radioassay data were measured using commonly available detection systems. The data were analyzed using a limited version of the overdispersion model developed earlier. In that limit, the relationships between three overdispersed distributions were derived and discussed: beta-Poisson, negative binomial, and overdispersed Gaussian. Out of a total of 13 cases studied (12 measured plus one from the literature), 4 were consistent with the Poisson statistics at 90% confidence level while the remaining 9 were found overdispersed. This shows that the overdispersion is rather prevalent in radioassay. All three overdispersed distributions fitted the data very well. The overdispersion was attributed mostly to the excess fluctuations of the detection systems or, in 2 cases, sequential radioactive decay.

Models, Statistical↗