Hortensius, L.M. (2010) The DAOA region is an effect modifier in predicting positive, negative and disorganized schizotypal symptoms in healthy participants. Master's thesis in Psychology, Utrecht University. (Thesis)
Peters, M., Field, C.L., Hortensius, L.M., Soper, J., Burco, J., Kelly, T.R. and Prager, K.C., 2025. Evaluation of Two Serologic Tests for Rapid Detection of Anti-Leptospira Antibodies in California Sea Lions (Zalophus californianus). Journal of Wildlife Diseases. 2025.
Zotto, S. N., Dunkin, R. C., Limon, J. D., Smith, M. S., Hortensius, L.M., Martinez, M. E., Duignan, P. J., Field, C., Soto, E., Whitaker, D., Rios, C., Byukusenge, M., Jayarao, B., Kuchipudi, S. V., & Kinsley, A. C. (2025). Klebsiella pneumoniae in stranded California sea lions (Zalophus californianus) of central California between 2017-2022. Frontiers in Marine Science, 11, 1484944. https://doi.org/10.3389/fmars.2024.1484944
Kane, L. P., Field, C. L., Hortensius, L.M., Rios, C., McClain, A. M., Whitmer, E. R., Simeone, C., Dennison, S., Zabrodski, M. W., & Duignan, P. (2025). Anthelmintic therapies for Parafilaroides decorus pneumonia in California sea lions (Zalophus californianus). Journal of Zoo and Wildlife Medicine, 56(3), 515–524.
Martinez, M., Hortensius, L.M., Takahashi, Y., Rios, C., Rivard, M., Prager, K., Field, C., Duignan, P., Hokamp, J., Wong, V. Reference intervals for renal biomarkers in free-ranging California sea lions (Zalophus californianus); Poster presentation at the American College of Veterinary Pathologists Annual Meeting (ACVP), October 25-28, 2025, New Orleans, LA.
Saunders, S., Aguirre, M., Hortensius, L.M., Field, C. Human-made marine debris removed from phocids at The Marine Mammal Center; Poster presentation at the American Fisheries Society Annual Meeting, September 15-19, 2024, Honolulu, HI.
Peters, M., Field, C.L., Hortensius, L.M., Soper, J., Burco, J., Kelly, T.R., Prager, K.C. Evaluation of two serologic tests for rapid diagnosis of Leptospira in California sea lions (Zalophus californianus); Oral presentation at the International Association of Aquatic Animal Medicine Conference, May 19-23, 2024, Galway Ireland.
Ortiz Colosi, A.W., Hortensius, L.M., Field, C.L. Review of perianesthetic mortality risk of stranded Northern elephant seals (Mirounga angustirostris) and Pacific harbor seals (Phoca vitulina richardsi) in central and northern California; Oral presentation at the International Association of Aquatic Animal Medicine Conference, May 19-23, 2024, Galway Ireland.
Taylor A., Shapiro K., Hortensius L.M., Packham A., Plancarte M., Conrad P., Smith W., Johnson C.K., Field C.L. Epidemiology and risk factors for Sarcocystis neurona and Toxoplasma gondii exposure in California sea lions (Zalophus californianus) from 2010-2019; Oral presentation at the Wildlife Disease Association Conference, July 29 - August 4, 2023, Athens, GA.
Hortensius, L.M. & Aguirre, M. Data management and sharing at the world's largest marine mammal hospital; Oral presentation at the 2023 American Statistical Association Conference on Statistical Practice, February 2023, San Francisco, USA.
Rivard, M., Hortensius, L.M., Norris, T. & Field, C.L. Causes and trends of live strandings of northern fur seals (Callorhinus ursinus) along the California coast, 1975-2021. Oral presentation at the Beyond the Golden Gate Research Symposium, January 2022, San Francisco, USA.
Hortensius, L.M. & Wang, C. Practical Guidelines for the Estimation of Multidimensional Ordered Polytomous Models. Oral presentation at the annual meeting of the National Council on Measurement in Education, April 2014, Philadelphia, USA. (Slides / Paper)
Hortensius, L.M. & Weiss, D.J. Small item bank CAT; Interaction of scoring method, termination criteria, and item bank shape. Oral presentation at the annual meeting of the International Association for Computerized Adaptive Testing, August 2012, Sydney, Australia. (Slides)
Hortensius, L.M. & Weiss, D.J. (2012, July). Computerized adaptive testing (CAT) design; Interaction of item bank, scoring method, and termination criteria. Poster presentation at the 8th meeting of the International Test Commission, July 2012, Amsterdam, The Netherlands. (Poster)
Simeone, C.A., Colitz, C.M.H., Colegrove, K.M., Field, C.L., Rios, C., Chandler, H.L., & Johnson, S.P. (2016). Subconjunctival antimicrobial poloxamer gel for treatment of corneal ulceration in stranded California sea lions (Zalophus californianus). Veterinary Ophthalmology, 1-9. (I provided free statistical analysis assistance, a minor contribution to the paper).
These are presentations and notes I wrote for classes or for teaching while at the University of Minnesota. I post these in the hope that they might help others understand the material. The presentations were made for classes and are not exhaustive or guaranteed to be correct. Sources are cited where possible but especially early presentations might lack sufficient citations.
Multidimensional calculus relevant to psychometrics (Presentation)
Statistical error and the impact of measurement error on statistical procedures (Presentation)
EM algorithm in the context of IRT item parameter estimation (Presentation)
Metropolis Hastings Markov Chain Monte Carlo (Presentation)
Putting a confidence interval around 'observed score' versus 'true score' in classical test theory (Notes)
Measurement Invariance in SEM (Class Paper)
Differential Item Functioning tests with R (Class Paper)
The Dirichlet distribution (Notes)