About Us
Who we are
About VPG
Vector Psychometric Group, LLC (VPG) was founded in 2007 as a psychometric consulting company and, in 2010, expanded its mission to offer state-of-the art psychometric, statistical, and data collection software. In 2020, VPG cemented its commitment to lead the market of advanced psychometric and data analytic software with the acquisition of Scientific Software International, Inc. In 2021, VPG further expanded its mission to incorporate top-tier qualitative research services to provide our clients with a “one-stop” shop for all phases of measurement development and modeling. Today, VPG comprises two business units, VPG Health and SSI, offering both contract research services and software focused on the statistical modeling of health, behavioral, and educational outcomes.
Leadership
R.J. Wirth,
PhD
R.J. Wirth is Chief Executive Officer, co-Founder, Consulting Psychometrician, and a Manager at VPG. Dr. Wirth received his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill
R.J. Wirth is Chief Executive Officer, co-Founder, Consulting Psychometrician, and a Manager at VPG. Dr. Wirth received his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill.
Prior to leading VPG, Dr. Wirth held research positions at the Frank Porter Graham Child Development Institute at The University of North Carolina and in the School of Medicine at the University of Washington. For nearly two decades, Dr. Wirth has collaborated widely within the pharmaceutical and medical device industries to develop and/or evaluate the measurement properties of clinical outcome assessments and was awarded (as co-PI) one of the first FDA-funded CDER pilot program grants: Standard core clinical outcome assessments and their related endpoints.
Dr. Wirth has authored numerous peer-reviewed publications on such topics as item factor analysis, structural equation modeling, validity, as well as various aspects of scale development appearing in outlets such as Headache, Health Psychology, Medical Care, Psychological Assessment, Psychological Methods, and Quality of Life Research. He has participated as an invited expert speaker on multiple FDA panels and industry advisory boards focused on COA development and support.
Li Cai,
PhD
Li Cai is Chief Scientific Officer, Consulting Psychometrician, and a Manager at VPG. He earned his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill.
Li Cai is Chief Scientific Officer, Consulting Psychometrician, and a Manager at VPG. He earned his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill.
Broadly speaking, his research agenda involves the development, integration, and evaluation of innovative latent variable models that have wide-ranging applications in educational, psychological, and health-related domains of study. A key component on this agenda is statistical computing, particularly as related to item response theory (IRT) and multilevel modeling. Dr. Cai has developed IRT software programs for item analysis and test scoring, such as IRTPRO and flexMIRT®, as well as the scoring engine behind VPG’s Adaptest®, a web-based pull-in for the administration and scoring of IRT-based, including adaptive, tests via commercially available EDC systems.
Michael C. Edwards,
PhD
Mike Edwards is Chief Financial Officer, co-Founder, Consulting Psychometrician, and a Manager at VPG. He earned his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill.
Mike Edwards is Chief Financial Officer, co-Founder, Consulting Psychometrician, and a Manager at VPG. He earned his PhD in Quantitative Psychology from the historic LL Thurstone Psychometric Laboratory at University of North Carolina – Chapel Hill.
His research is generally focused on modern psychometrics with specific emphases on item response theory (IRT), factor analysis, and issues related to dimensionality. Dr. Edwards has published over 60 peer-reviewed articles, nine chapters, and given over 70 presentations. His published work appears in a range of outlets including Autism, Journal of Abnormal Psychology, Journal of Clinical Epidemiology, Psychological Assessment, Psychological Methods, Psychometrika, and Quality of Life Research. He is currently serving as an Associate Editor for Psychological Methods.
In addition to his roles at VPG, Dr. Edwards has been a faculty member at Arizona State University since 2017. He is a Professor in the Quantitative Research Methods program within the Department of Psychology. Prior to that, he was an Assistant and Associate Professor in the Department of Psychology at The Ohio State University. While at OSU, he was chair of the Social and Behavioral Sciences institutional review board (IRB), which has enabled him to gain insight into important ethical considerations around data and privacy.
Leaders in the field of Psychometrics
• Presidential Early Career Award for Scientists and Engineers (Dr. Cai, 2012)
• Anne Anastasi Early Career Award from American Psychological Association (Dr. Cai, 2011)
• Key Opinion Leader on Clinical Outcome Assessments and Digitally Derived Outcomes (Dr. Wirth)
• Key Opinion Leader on Evidence-based Rationale (Dr. Edwards)
• One of the most often cited psychology/psychometric papers (top 1%) in recent years (Wirth & Edwards, 2007)
• flexMIRT® & IRTPRO™ are used worldwide by numerous educational testing, accreditation, licensure, and regulatory organizations (both programs were developed by Dr. Cai and colleagues)
• Various Industry Advisory Boards (Educational Testing, Dr. Cai; Certification Exams, Dr. Edwards; Pharmaceutical, Dr. Wirth)
Fast Facts
- Vector Psychometric Group, LLC is focused on improving and implementing psychometric and behavioral analytics methods. We take great pride in our work and provide clients with top-tier service.
- We specialize in longitudinal measurement models (e.g., stability of measurement structure over time) and discrete data (e.g., trajectory of symptom severity over time)
- VPG has been providing clients with high-quality support and deliverables since 2007. Our focus is on assisting our clients’ achieve their psychometric and regulatory goals and moving the field of assessment forward
