Research Portfolio
Journal Publications
A selection of my peer-reviewed journal articles:
- Helwig, N. E., Chen K., Guy S. J., & Lyford-Pike S. (2026) Regularized multilevel multinomial regression for select-all-that-apply responses and high-dimensional predictors with applications to perception of facial expressions. Psychometrika DOI: 10.1017/psy.2026.10102 .
- Delgado, J. E., Elison, J. T., & Helwig, N. E. (2025). Robust detection of signed outliers in multivariate data with applications to early identification of risk for autism. Psychological Methods. DOI: 10.1037/met0000775
- Helwig, N. E. (2025). Versatile descent algorithms for group regularization and variable selection in generalized linear models. Journal of Computational and Graphical Statistics. DOI: 10.1080/10618600.2024.2362232
- Helwig, N. E. (2019). Statistical nonparametric mapping: Multivariate permutation tests for location, correlation, and regression problems in neuroimaging. WIREs Computational Statistics. DOI: 10.1002/wics.1457
See the Publications page for a complete list of my peer-reviewed publications.
Software Packages
A selection of my open-source software packages:
- grpnet: Group Elastic Net Regularized GLMs and GAMs. DOI: 10.32614/CRAN.package.grpnet
- npreg: Nonparametric Regression via Smoothing Splines. DOI: 10.32614/CRAN.package.npreg
- nptest: Nonparametric Bootstrap and Permutation Tests. DOI: 10.32614/CRAN.package.nptest
- multiway: Component Models for Multi-Way Data. DOI: 10.32614/CRAN.package.multiway
See the Software page for a complete list of my software packages.
Conference Talks
A selection of my conference and workshop talks:
- Helwig, N. E. (2025, December 3). Improving science via artificial intelligence. Part 1: introduction to GenAI and LLMs. Quantitative and Psychometric Methods Seminar, University of Minnesota.
- Helwig, N. E. (2025, November 12). Developing open-source software. Quantitative and Psychometric Methods Seminar, University of Minnesota.
- Helwig, N. E. (2025, July 16). Group elastic net regression: a framework for high-dimensional regression and classification of psychological data. International Meeting of the Psychometric Society, Minneapolis, MN.
- Helwig, N. E. (2019, Mar. 8). Reproducible data wrangling and modeling with R. Department of Psychology Open and Reproducible Science Brown Bag Series, University of Minnesota.
See the Talks page for a complete list of my conference talks.