Research

Macroevolution. Using statistical analysis and paleontological databases, I study large-scale questions about the history of life. Sample questions include: (1) Are mass extinctions merely larger manifestations of processes responsible for background extinction, or are they a fundamentally different phenomenon? (2) How many kinds of dinosaurs ever lived, and were dinosaurs already declining before an impact at the end of the Cretaceous Period caused their ultimate extinction? (3) Are observed extinction rates in mass extinctions a reliable guide to the severity of the triggering mechanism? That is, does a higher extinction rate indicate a more severe cause, or can factors such as Simpson's paradox make such an inference misleading?

Dynamics of extinction in food webs. The end-Permian mass extinction was the most severe in the history of life, but its causes remain enigmatic. With Peter Roopnarine of the California Academy of Sciences and Ken Angielczyk of the Field Museum, I study the dynamics of extinction in terrestrial ecosystems during the Permian. Using models of Permian food webs, we explore how the extinction of primary producers (e.g. green plants) could have led to the collapse of terrestrial ecosystems. More generally, we study factors leading to stability or instability in ecosystems.


More information:   Publications   |   Media coverage   |   Talks   |   Lab members and collaborators   |   Grant funding   |   Google scholar page

Other areas of interest:

Watch a video of my talk at TEDxSwarthmore.

Statistical graphics and visualization. I am interested in how to effectively visualize high-dimensional datasets using graphical methods such as parallel axis plots and data image plots, and more generally in principles of effective graphical representation and communication.

Statistical methods in baseball research, also known as sabermetrics. I am interested in the analysis of managerial strategies (featured in the New York Times and the Philadelphia Inquirer; also see here for additional media coverage). My MS paper was on a Markov Chain model for baseball lineups and player evaluation, with advisor Michael Stein. Read an interview with me on the growing use of statistical analysis in baseball.

Opportunities for students: In most years, I have openings for one or more summer student researchers for various projects on statistical paleontology. Please email me if you are interested. Due to grant restrictions, eligibility is usually limited to Swarthmore students. The preferred prerequisites are Stat 61 and CS 21 (or equivalent), but some combination of Stat 11, Stat 31, Bio 2, or other experience may suffice as well. No paleontology background is necessary. Learn more about projects and publications by previous students.

Teaching

I was awarded the 2008 Waller Education Award from the American Statistical Association for innovation in the instruction of elementary statistics.

Requesting a letter of recommendation from me? Please read this page first.

Biographical info

Contact info