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My specific interests within the area of research design is primarily focused on issues of sample size planning. In particular, I focus on the interplay between sample size planning for statistical power and sample size planning for statistical accuracy (i.e., accuracy in parameter estimation; Read more here). This area largely concerns the estimation and testing of effect size measures and their corresponding confidence intervals. My specific interest within the context of longitudinal data analysis is on the use of nonlinear multilevel models and modeling change in situations where hypothesized but unknown heterogeneity exists (Read more here.).

My research interests in quantitative methodology is quite broad. Some of the other topics applicable to the methodology that I work on or have a real interest in are general latent variable modeling (e.g., structural equation modeling; growth mixture modeling), multilevel models, statistical classification and statistical discrimination, computational statistics (e.g., the bootstrap technique; design and implementation of Monte Carlo simulation studies), and measurement issues. It turns out that my work largely involves the combination of these methods so that substantive questions can be addressed with methodologically sound techniques and procedures, and so that existing methods can be extended and generalized.