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I have a diverse background in both methodological and applied research across various fields and topics. My research applications include aging, mental health, sleep, and addiction. I am particularly focused on methodologies that address challenges relating to sparse data and data with significant measurement error, particularly in the context of modeling and latent subpopulation identification. I am also passionate about wearable device data and EMA + smartphone data. My work is motivated by a strong commitment to addressing public health issues and making a meaningful impact.
Research Areas and Projects
Research Areas and Projects
Methodological and Aging-Related Projects
Methodological and Aging-Related Projects
Dynamical systems modeling & Physical Resilience [dissertation-related]: I work primarily with Dr. Karen Bandeen Roche on developing methodology for dynamical systems modeling in the sparse-data context. We are motivated by the concept of physical resilience in older adults. Our ultimate goal is to test hypotheses underlying physical resilience-- we aim to characterize its pathways and presence in older adults.
Pre-frailty [dissertation-related]: We are assessing the hypothesis that physical frailty is an intermediate state and prodrome of physical frailty in older adults using clustering methods and modeling. This work involves careful handling of data with measurement error.
Collaborative: I have worked with fellow graduate students in the epidemiology and mental health departments to better understand measurement error and its role in misclassifying physical frailty, specifically in the context of clinical depression.
Wearable Device Projects
Wearable Device Projects
Sleep and Behavior in Adolescents: I worked with a team to use population-level cohort data from the ABCD Study. We utilized Fitbit sleep data and reported measurements of externalizing behaviors to better understand understand their link.
Heart Rate and Psychological Measurements in Patients: I worked with a team utilizing WHOOP device data to understand trends in heart rate and psychological measurements over the course of treatment for addiction.
EMA Projects
EMA Projects
Addiction and Substance Use: I have worked on multiple projects utilizing Ecological Momentary Assessment data from a study of participants with chronic pain who take cannabis and opioids. We used Group Iterative Multiple Model Estimation (GIMME) to better understand triggers behind substance usage and how patterns of usage vary between individuals.
Research at AstraZeneca
The summer of 2025 I spent 12 weeks working within the Statistical Innovation group (housed within Oncology Biometrics) at AstraZeneca. My primary research surrounded evaluating methods for biomarker selection, with applications in early phase drug development and clinical trial recruitment.
Papers
Papers
Published
McKendrick G, Clapham C, Zipunnikov V, et al. Effects of suvorexant on diurnal cortisol and patient-reported stress during opioid withdrawal in a randomized trial. Psychoneuroendocrinology. 2025;180:107570. doi:10.1016/j.psyneuen.2025.107570
Submitted & Under Review
Charlotte Clapham, I-Tzu Hung, PhD, Nicole Tacugue, Brion S. Maher, PhD, Vadim Zipunnikov, PhD, Joe Kossowsky, PhD, Jill A. Rabinowitz, PhD. REM Deficiency and Increased Sleep Fragmentation is Associated with Externalizing Behaviors and ADHD Symptoms in Adolescents (2025+).
Charlotte Clapham, Bryant M. Stone, PhD, Cerina Dubois, PhD, Clarissa Madar, Kelly E. Dunn, PhD, Vadim Zipunnikov, PhD, Ryan Vandrey, PhD, Patrick H. Finan, PhD, Amicie Koslow, Janardan Devkota, MS, MPH, Brandon T. Sanford, PhD, Johannes Thrul, PhD. Opioids Drive Cannabis Craving and Use Patterns in Patients with Chronic Pain: An Application of Group Iterative Multiple Model Estimation Analysis (2025+).
Bryant M. Stone, PhD, Charlotte Clapham, Janardan Devkota, MS, Kelly Dunn, PhD, Vadim Zipunnikov, PhD, Ryan G. Vandrey, PhD, Patrick Finan, PhD, Johannes Thrul, PhD. The Hidden Consequences of Disengaged Respondents in Ecological Momentary Assessment Studies: Identification, Characterization, & Implications (2025+).
Bryant M. Stone, PhD, Cerina Dubois, PhD, Charlotte Clapham, Janardan Devkota, M.S., Kelly Dunn, PhD, Vadim Zipunnikov, PhD, Ryan G. Vandrey, PhD, Patrick Finan, PhD, Johannes Thrul, PhD. Reward Fairness May Be the Hidden Catalyst of Response Rates in Ecological Momentary Assessment Studies (2025+).
In Preparation
Charlotte Clapham, Ravi Varadhan, PhD, Karen Bandeen-Roche, PhD. Modeling and Design for Physiologic Systems Data (2025+).
Charlotte Clapham, Karen Bandeen-Roche, PhD. New Perspectives on Prefrailty (2025+).
Wendy Insalaco, PhD, Charlotte Clapham, Brett Gelino, PhD, Jami Mayo, Joseph Hobelmann, MD, Andrew Huhn, PhD, Jill A. Rabinowitz, PhD, Vadim Zippunikov, PhD. Tracking the Longitudinal Course of Physiologic and Mental Health Functioning among Individuals in Substance Use Disorder Treatment (2025+).
Oral Presentations
Oral Presentations
Charlotte Clapham, Ravi Varadhan, PhD, Karen Bandeen-Roche, PhD. Modeling and Design for Physiologic Systems Data. Joint Statistical Meetings (JSM). Portland, OR. August 6, 2024.
Charlotte Clapham, Ravi Varadhan, PhD, Karen Bandeen-Roche, PhD. Modeling and Design for Physiologic Systems Data. Johns Hopkins Biostatistics Department Seminar. Baltimore, MD. September 6, 2024.
Poster Presentations
Poster Presentations
Charlotte Clapham, Karen Bandeen-Roche, PhD. New Perspectives on Prefrailty. Research on Aging Showcase. Johns Hopkins University, Baltimore, MD. May 16, 2025.
Charlotte Clapham, Karen Bandeen-Roche, PhD. Design and Analysis Implications for Local Linear Approximation of Dynamical Physiological Systems Data. Eastern North American Region (ENAR). New Orleans, LA. March 24, 2025.
Charlotte Clapham, Ravi Varadhan, PhD, Karen Bandeen-Roche, PhD. Design and Modeling for Sparsely Sampled Physiologic Systems Data. Gerontological Society of America (GSA). Seattle, WA. November 16, 2024.
Charlotte Clapham, Joe Kossowsky, PhD, Danielle A Wallace, PhD, Amélie V Martin, PhD, Brion Maher, PhD, Jill A. Rabinowitz, PhD, Vadim Zipunnikov, PhD. Associations of Objectively-Measured Sleep Metrics with ADHD and Externalizing Symptoms in the Adolescent Brain Cognitive Development Study. The Johns Hopkins Sleep & Circadian Research Day. Johns Hopkins University, Baltimore, MD. May 20, 2024.
Charlotte Clapham, Ravi Varadhan, PhD, Karen Bandeen-Roche, PhD. Modeling and Design for Physiologic Systems Data. Research on Aging Showcase. Johns Hopkins University, Baltimore, MD. April 5, 2024.
Community Involvement and Leadership
Community Involvement and Leadership
- Co-President of the Biostatistics Student Organization [September 2023- August 2025]
Representative of the Mental Health Graduate Network [August 2023- present]
Partnership with the Baltimore ToolBank [September- December 2023]
Student Representative of Johns Hopkins Biostatistics across various recruitment events
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