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Akihito Kamata

Publications and source records attributed to Akihito Kamata.

3 recordsLinked to original sources

Inference for Error-Prone Count Data: Estimation under a Binomial Convolution Framework

Measurement error in count data is common but underexplored in the literature, particularly in contexts where observed scores are bounded and arise from discrete scoring processes. Motivated by applications in oral reading fluency assessment, we propose a binomial convolution framework that extends binary misclassification models to settings where only the aggregate number of correct responses is observed, and errors may involve both overcounting and undercounting the number of events. The model accommodates distinct true positive and true negative accuracy rates and preserves the bounded nature of the data. Assuming the availability of both contaminated and error-free scores on a subset of items, we develop and compare three estimation strategies: maximum likelihood estimation (MLE), linear regression, and generalized method of moments (GMM). Extensive simulations show that MLE is most accurate when the model is correctly specified but is computationally intensive and less robust to misspecification. Regression is simple and stable but less precise, while GMM offers a compromise in model dependence, though it is sensitive to outliers. In practice, this framework supports improved inference in unsupervised settings where contaminated scores serve as inputs to downstream analyses. By quantifying accuracy rates, the model enables score corrections even when no specific outcome is yet defined. We demonstrate its utility using real oral reading fluency data, comparing human and AI-generated scores. Findings highlight the practical implications of estimator choice and underscore the importance of explicitly modeling asymmetric measurement error in count data.

stat.ME↗

Penalized Likelihood Methods for Modeling Count Data

The paper considers parameter estimation in count data models using penalized likelihood methods. The motivating data consists of multiple independent count variables with a moderate sample size per variable. The data were collected during the assessment of oral reading fluency (ORF) in school-aged children. A sample of fourth-grade students were given one of ten available passages to read with these differing in length and difficulty. The observed number of words read incorrectly (WRI) is used to measure ORF. Three models are considered for WRI scores, namely the binomial, the zero-inflated binomial, and the beta-binomial. We aim to efficiently estimate passage difficulty, a quantity expressed as a function of the underlying model parameters. Two types of penalty functions are considered for penalized likelihood with respective goals of shrinking parameter estimates closer to zero or closer to one another. A simulation study evaluates the efficacy of the shrinkage estimates using Mean Square Error (MSE) as metric. Big reductions in MSE relative to unpenalized maximum likelihood are observed. The paper concludes with an analysis of the motivating ORF data.

stat.ME↗

An EM Algorithm for Estimating an Oral Reading Speed and Accuracy Model

This study proposes a two-part model that includes components for reading accuracy and reading speed. The speed component is a log-normal factor model, for which speed data are measured by reading time for each sentence being assessed. The accuracy component is a binomial-count factor model, where the accuracy data are measured by the number of correctly read words in each sentence. Both underlying latent components are assumed to be Gaussian in nature. In this paper, the theoretical properties of the proposed model are developed and an Monte Carlo EM algorithm for model fitting is outlined. The predictive power of the model is illustrated in a real data application.

stat.AP↗