Criminology & Social Data Analytics·Penn State
Siyang Ni
I study how self-control develops from childhood through adolescence, and how that development shapes delinquency, substance use, and contact with the justice system.
My work draws on longitudinal models, quasi-experimental designs, and machine learning. I also write open-source software so other researchers can run advanced longitudinal models without proprietary tools.
- 3papers under review
- 3dissertation papers, one argument
- 2research tools in active use
- 1course taught as instructor of record
Job market paper
Course, Not Type
Self-Control Development From Childhood to Adolescence and Criminal Justice Contact at Age 23
How a child’s self-control changed between ages 5 and 17 predicts formal contact with the criminal justice system by age 23. The data show no distinct high-risk group of children behind that prediction. Risk differs by degree, not by kind of child.
Selected work
Research and software beyond the dissertation
Adolescent substance use
As teen vaping declined, it became a marker of other substance use more than of smoking. Two papers under review at Nicotine & Tobacco Research.
About this work Under reviewParental migration and delinquency
In rural China, adolescents with one migrant parent, not two, reported higher expected delinquency than those with no migrant parent.
About this work R packagesurveymixr
Growth mixture models in R that account for survey weights, clusters, and strata. Before it, fitting these models correctly meant using Mplus.
About the package DashboardAmerican Authorship Database
An R Shiny application for a historical publishing archive, still used by the Penn State College of the Liberal Arts.
About the dashboardMaterials
Application materials
- Curriculum vitae PDF, September 2026
- Job market paper Full draft available on request
- Research statement Available on request
- Teaching statement Available on request
- Conference poster Society for Research on Adolescence, April 2024
Contact
Get in touch
To request materials or ask about my work, send a message here or email siyangni@psu.edu.