Dr. Laura Cowen
Associate Professor
Department of Mathematics and Statistics
University of Victoria
P.O. Box 3060 STN CSC
Victoria, B.C. V8W 3R4

EMAIL: lcowen (a t)
PHONE: (250) 721-6152
OFFICE: David Turpin Building A446
FAX: (250) 721-8962

Research Interests
I am an ecological statistician with a research focus in mark-recapture methods and applications.  In particular I am interested in tag loss and how it can be incorporated into models directly. I work on real world problems, mainly pertaining to fishery studies.

My major focus of research is mark-recapture methodology and applications in both fisheries and public health.  Mark-recapture experiments are used widely by fisheries biologists, wildlife managers and ecologists as a method of estimating population numbers, survival, recruitment, and migration rates. Animals are captured, given a unique mark and released. Subsequent recaptures, resightings, or recoveries (of carcasses) provide information on survival, abundance and if of interest migration. Data are in the form of capture histories; for example, a {101} capture history would indicate an animal tagged at time 1, not seen at time 2, and recaptured at time 3. One of the major assumptions inherent to all mark-recapture experiments is that animals do not lose their tags. Often it is assumed that tag loss is negligible. Consequently a {110} capture history with tag loss could be misinterpreted as mortality when not seen at time 3. A violation of the no-tag-loss assumption causes bias in parameter estimates and their standard errors because mortality and tag loss cannot be separated.
I am also involved in the Population Research Group at the University of Victoria.  Here I have been involved in several projects that investigated needle sharing behaviour of people who use injection drugs in Victoria, B.C. and in estimating the number of injection drug users in Victoria.  

Graduate Students
If you are interested in becoming a graduate student at UVic and you are interested in ecological statistics then please contact me!
Status/ Year Graduated
Yuan Xu
MSc- Statistics
Rock lobseter abundance estimation using the Jolly-Seber-Tag-Loss model with group heterogeneity
Ryan Stone
MSc- Statistics
Modeling Victoria's injection drug users.
Emily Malcolm MSc- Statistics The effect of recycled individuals in the Jolly-Seber model with tag loss. 2014
Paul van dam Bates
MSc- Statistics
Movement and containment of the California sea cucumber (Parastichopus californicus) in relation to organically-enrished areas beneath aquaculture sites
Lu Wang
MSc- Statistics
Minimum chi-square method for estimating population size with Capture-Recapture data.
Yu Wang
MSc- Statistics
The Jolly-Seber-tag-loss model: a state-space formulation.
Ahmed Hoque PhD- Economics and Statistics On estimating variances for Gini coefficients with complex surveys: Theory and applications. 2016
Yongfei Mao
MSc- Statistics
Exploring the minimum chi-square method for multiple-occasion Capture-Recapture data.
Yuyan Yang
MSc- Statistics Is ocean colour spectra acquired by ferry passengers robust for science applications?
Yan Xu
MSc- Statistics A state-space formulation of the Jolly-Seber model with dependent tag loss.
Yuyan Zheng MSc- Statistics Minimum chi-square estimation of a white stork population. 2018
Mathew Parker
MSc- Statistics An R package for extended batch marking data.
Sofia Romanovska MSc- Statistics Evaluating citizen science golden eagle migration data collected by the Rocky Mountain Eagle Research Foundation, Mount Lorette, Alberta 1993-2016
Ben Liu MSc- Statistics Analysis of golden eagle migration counts, Mount Lorette, Alberta 1993-2016 Current
Rhonda Reidy PhD- Biology The role of humpback whale predation on commercial fish population dynamics in British Columbia. Current

Undergraduate Students
If you are interested in becoming an undergraduate research student then please contact me!
Selina Gonzalez
BSc- Economics and Statistics
The Jolly-Seber-Tag-Loss model with group heterogeneity.
Dean Koch
BSc- Math/Stat and Biology
Comparing growth rates of Cassin's Auklet chicks on Frederick and Triangle Island, BC.
Dean Koch
BSc- Math/Stat and Biology
Comparing the wiggliness of two spline models.
Stephanie Yurchak
BSc- Math/Stat
Parameter redundancy in tag-loss models.
Robin Spillette
BSc- Math/Stat
Capture-Recapture analysis of invasive Canadian goose population.
Jovan Allen
BSc- Economics and Statistics
Simulation studies in mark-recapture models.
Jo Cai
BSc- Financial Mathematics and Economics
Parameter redundancy in tag-loss models II.
Jo Cai
BSc- Financial Mathematics and Economics Evaluating drivers of harmful algae.

Articles Published

Cowen, L.L.E., P.T. Besbeas, B.J.T. Morgan, C.J. Schwarz. 2017. Hidden Markov Models for Extended Batch Data. Biometrics, 73, 1321-1331.
Bertram D.F., A. Harfenist, L.L.E. Cowen, D. Koch, M.C. Drever, J.M. Hipfner, and M.J.F. Lemon. 2017. Latitudinal temperature-dependent variation in timing of prey availability can impact Pacific seabird populations in Canada. Canadian Journal of Zoology, 95: 161-167.

van Dam-Bates, P., D.L. Curtis, L.L.E. Cowen, S.F. Cross, and C.M. Pearce. 2016. Assessing movement of the California sea cucumber (Parastichopus californicus) in response to organically-enriched areas typical of aquaculture sites. Aquaculture Environment Interactions, 8, 67-76.

van Dam-Bates, P., M. Fyfe, and L.L.E. Cowen. 2015. Applying open population capture-recapture models to estimate the abundance of injection drug users in Victoria, Canada. Journal of Substance Use, early online, 1-6.

Rigby, P.C., D.M. German, L. Cowen, and M.-A. Storey. 2014. Peer review on open source software projects: parameters and statistical models. ACM Transactions on Embedded Computing Systems. 23(4), 35:1-33.

Xu, Y., M. Fyfe, L. Walker, and L.L.E. Cowen. 2014. Estimating the number of injection drug users in greater Victoria, Canada using capture-recapture methods. Harm Reduction J. 11:9.
Cowen, L.L.E., P. Besbeas, B.J.T. Morgan, C.J. Schwarz. 2014. A comparison of abundance estimates from extended batch-marking and Jolly-Seber type experiments. Ecology and Evoluation. 4, 210-218.

Cowen, L.L.E., W.O. Challenger, and C.J. Schwarz. 2014. What do salmon and injection drug users have in common? Statistical Society of Canada's special issue in Statistics in Action: A Canadian Outlook. J.F. Lawless editor. Chapman and Hall/CRC Press. 269-288.

Xu, Y., L.L.E. Cowen, and C. Gardner. 2014. Group Heterogeneity in the Jolly-Seber-Tag-Loss Model. Statistical Methodology. 17, 3-16.

Smith, B.C., Simpson, Y., Morshed, M., Cowen, L.L.E., Hof, R., Wetherell, C. Boulanger, M.J., Cameron, C.E. Syphilis diagnosis – new proteins for a new perspective. Journal of Clinical Microbiology, 51, 105-111.

Gonzalez, S. and L. Cowen. 2010. The Jolly-Seber-Tag-Loss Model with group heterogeneity. The Arbutus Review, 1, 30-42.

Exner, H., E.K. Gibson, R. Stone, J. Lindquist, L. Cowen and E.A. Roth, 2010. A mixed methods approach to delineating and understanding injection practices among clientele of a Victoria, British Columbia needle exchange program. Drug Alcohol Rev., 30, 360-365. DOI: 10.1111/j.1465-3362.2010.00219.x

Blight, L.K, T. D. Williams, D. F. Bertram, and L. Cowen.   Interannual variation in egg neglect and incubation routine of the Rhinoceros Auklet (Cerorhinca Monocerata) during the 1998-1999 El Nino/ La Nina events.  Marine Ornithology. 38, 11-15.

Eshghi, A., P. A. Cullen, L. Cowen, and C. E. Cameron. 2009.   Global proteome analysis of Leptospira interrogans cultured in vivo-like media.  J Proteome Research. Published online August 10.

Exner, H., E.K. Gibson, R. Stone, J. Lindquist, L. Cowen and E.A. Roth. 2009.  Worry as a window into the lives of people who use injection drugs: A factor analysis approach.   Harm Reduction J. 6-20.

Cowen, L., S. J. Walsh, C. J. Schwarz, N. Cadigan and J. Morgan. 2009.  Estimating exploitation rates of a migrating population of yellowtail flounders using multi-state mark-recapture methods incorporating tag-loss and variable reporting rates.  Can. J. Fish. Aquatic Sc. 66, 1245-1273.

Cowen, L., N. Trouton, and R. E. Bailey.  2007. Effects of angling on Chinook salmon for the Nicola River, British Columbia, 1996-2002.  N. Am. J. Fish Manage. 27, 256-267.

Cowen, L. and C. J. Schwarz. 2006.  The Jolly-Seber model with tag loss.  Biometric. 62, 699-705.

Cowen, L. and C. J. Schwarz. 2005. Capture-recapture studies using radio telemetry with premature radio-tag failure. Biometrics. 61, 657-664.

Fraser, G. S., I. L. Jones, F. M. Hunter, and L. Cowen. 2004. Mate switching patterns in Crested Auklets (Aethia Cristatella): The role of breeding success and ornametation. Bird Behavior. 16, 1-6.

Cowen, L. and W. F. Bobier. 2003.  Defining the astigmatism in a pre-school population using the Retinomx Plus autorefractor. Invest. Ophth. Vis Sci. 44, 4593-4600.

Hedd, A., J. L. Ryder, L. Cowen, and D. F. Bertram. 2002. Inter-annual variation in the diet, provisioning, and growth of Cassin's Auklet at Triangle Island, British Coumbia: Resonses to variation in ocean climate? Mar. Ecol-Prog. Ser. 229, 221-232.

Bertram, D. F., L. Cowen, and A. Burger. 1999. Use of radar for monitoring colonial burrow nesting seabirds. J. Field Ornithol. 70, 145-157.