Mary D. Sammel, ScD
|Office Location||605, Blockley Hall|
|CCEB Appointment||Senior Scholar, Biostatistics|
|Primary Faculty Appointment||Professor of Biostatistics at HUP, University of Pennsylvania Perelman SOM|
Dr. Sammel's statistical specialties are in the area of multivariate and longitudinal data methods, as well as analysis of mixtures of discrete and continuous data. Research content areas of interest include environmental and reproductive health. Dr. Sammel has extensive experience as a data analyst and has worked with a variety of biomedical investigators.
Dr. Sammel's current work is in the area of latent variable modelling where the focus is to reduce multivariate data to a smaller number of dimensions and estimate the impact of covariates. This is one way to address the issue of multiple testing for multivariate data. It also provides a means for producing a relative ranking of the subjects with respect to the latent variable. Current manuscripts in progress will evaluate the performance of this global test to standard methods. Work is also in progress to expand programs to deal with ordered categorical responses which are commonly used to develop health scales.
Sammel, M.D., and Ryan, L.M.: "Latent Variable Models with Fixed Effects," Biometrics, 52:650-663, 1996.
Sammel, M.D., Ryan, L.M., and Legler, J.M.: "Latent Variable Models for Mixed Discrete and Continuous Outcomes," Journal of the Royal Statistical Society, Series B, 59:667-678, 1997.
Xu, X., Cho, S-I., Sammel, M.D., You, L., Cui, S., Huang, Y., Wang, Z., Ma, G., Huang, W., Padungtod, C., Pothier, L., Christiani, D., Smith, T., Ryan, L., and Wang, L.: "Associations of Petrochemical Exposure with Spontaneous Abortion," Occupational and Environmental Medicine, 55:31-36, 1998.
Sammel, M.D., Lin, X., and Ryan, L.M.: "Multivariate Linear Mixed Models for Multiple Outcomes," Statistics in Medicine, to appear.
Sammel, M.D. and Landis, J.R. "Summarizing Mixed Outcomes for Pain in Interstitial Cystitis: A Latent Variable Approach," Proceedings of the International Biometric Conference, Cape Town, South Africa, December 1998.