Generalized additive models and inflated type I error rates of smoother significance tests

Constrained Generalized Additive Models for Zero-Inflated Data

Zero-inflated data abound in ecological studies as well as in other scientific and quantitative fields. Nonparametric regression with zero-inflated response may be studied via the Zero-Inflated Generalized Additive Model (ZIGAM). ZIGAM assumes that the response variable follows a probabilistic mixture distribution of a zero atom and a regular component whose distribution belongs to some 1-param...

Generalized Likelihood Ratio Tests for Additive Models

Naive application of permutation testing leads to inflated type I error rates.

Failure to account for family structure within populations or in complex mating designs via uninformed applications of permutation testing will lead to inflated type I error rates. Careful consideration of the design factors is essential since some situations allow several valid permutation strategies, and the choice that maximizes statistical power will not always be intuitive.

Generalized additive models and Lucilia sericata growth: assessing confidence intervals and error rates in forensic entomology.

Forensic entomologists use blow fly development to estimate a postmortem interval. Although accurate, fly age estimates can be imprecise for older developmental stages and no standard means of assigning confidence intervals exists. Presented here is a method for modeling growth of the forensically important blow fly Lucilia sericata, using generalized additive models (GAMs). Eighteen GAMs were ...

Bayesian generalized additive models for location, scale and shape for zero-inflated and overdispersed count data

Frequent problems in applied research that prevent the application of the classical Poisson log-linear model for analyzing count data include overdispersion, an excess of zeros compared to the Poisson distribution, correlated responses, as well as complex predictor structures comprising nonlinear effects of continuous covariates, interactions or spatial effects. We propose a general class of Ba...