@article{feng_xiao_li_chen_ohuma_2020, title={Correlation models for monitoring fetal growth}, volume={29}, ISSN={["1477-0334"]}, DOI={10.1177/0962280220905623}, abstractNote={ Ultrasound growth measurements are monitored to evaluate if a fetus is growing normally compared with a defined standard chart at a specified gestational age. Using data from the Fetal Growth Longitudinal Study of the INTERGROWTH-21st project, we have modelled the longitudinal dependence of fetal head circumference, biparietal diameter, occipito-frontal diameter, abdominal circumference, and femur length using a two-stage approach. The first stage involved finding a suitable transformation of the raw fetal measurements (as the marginal distributions of ultrasound measurements were non-normal) to standardized deviations (Z-scores). In the second stage, a correlation model for a Gaussian process is fitted, yielding a correlation for any pair of observations made between 14 and 40 weeks. The correlation structure of the fetal Z-score can be used to assess whether the growth, for example, between successive measurements is satisfactory. The paper is accompanied by a Shiny application, see https://lxiao5.shinyapps.io/shinycalculator/ . }, number={10}, journal={STATISTICAL METHODS IN MEDICAL RESEARCH}, author={Feng, Yuan and Xiao, Luo and Li, Cai and Chen, Stephanie T. and Ohuma, Eric O.}, year={2020}, month={Oct}, pages={2795–2813} }
 @article{blanchard_nakamura_cao_chen_moreau_2020, title={Spine and dine: A key defensive trait promotes ecological success in spiny ants}, volume={10}, ISSN={["2045-7758"]}, DOI={10.1002/ece3.6322}, abstractNote={Abstract}, number={12}, journal={ECOLOGY AND EVOLUTION}, author={Blanchard, Benjamin D. and Nakamura, Akihiro and Cao, Min and Chen, Stephanie T. and Moreau, Corrie S.}, year={2020}, month={Jun}, pages={5852–5863} }
 @article{chen_xiao_staicu_2019, title={A smoothing-based goodness-of-fit test of covariance for functional data}, volume={75}, ISSN={["1541-0420"]}, DOI={10.1111/biom.13005}, abstractNote={Abstract}, number={2}, journal={BIOMETRICS}, publisher={Wiley}, author={Chen, Stephanie T. and Xiao, Luo and Staicu, Ana-Maria}, year={2019}, month={Jun}, pages={562–571} }
 @article{chen_morgan_beresford_getz_christopher_langstrom_strickland_wiggenhorn_lyapustina_2019, title={Performance of the Population Bioequivalence (PBE) Statistical Test with Impactor Sized Mass Data}, volume={20}, ISSN={["1530-9932"]}, DOI={10.1208/s12249-019-1507-8}, abstractNote={This article extends previous work studying performance characteristics of the population bioequivalence (PBE) statistical test recommended by the US Food and Drug Administration (FDA) for orally inhaled and nasal drug products. Based on analysis of a metered dose inhaler database for impactor sized mass, a simulation study was designed to compare performance of the recommended PBE approach with several modified or alternative approaches. These included an extended PBE that separately modeled within-batch (can) and between-batch (batch) variability and average bioequivalence (ABE) tests that modeled with or without between-batch variability and with or without log-transformation. This work showed that separately modeling within- and between-batch variability while increasing the number of sampled batches addressed previously identified issues of the PBE approach when between-batch variability was present, namely, (a) increased risk for falsely concluding equivalence and (b) low probability of correctly concluding equivalence. The same modifications were also required of the ABE to achieve expected performance. However, these modifications did not successfully address the issue of equivalence conclusions that depended on the direction of product mean differences (asymmetric performance). This work highlights the importance of understanding decision-making error rates in developing regulatory recommendations to standardize bioequivalence outcomes across products.}, number={7}, journal={AAPS PHARMSCITECH}, author={Chen, Stephanie and Morgan, Beth and Beresford, Hayden and Getz, Elise Burmeister and Christopher, David and Langstrom, Goran and Strickland, Helen and Wiggenhorn, Christopher and Lyapustina, Svetlana}, year={2019}, month={Oct} }
 @article{chen_luo_hou_raubenheimer_ji_jin_jiang_yu_wang_li_et al._2018, title={Nutrient Balancing by Captive Golden Snub-Nosed Monkeys (Rhinopithecus roxellana)}, volume={39}, ISSN={["1573-8604"]}, DOI={10.1007/s10764-018-0070-6}, number={6}, journal={INTERNATIONAL JOURNAL OF PRIMATOLOGY}, author={Chen, Stephanie T. and Luo, Xi and Hou, Rong and Raubenheimer, David and Ji, Weihong and Jin, Xuelin and Jiang, Zhi and Yu, Xuewei and Wang, Jiajia and Li, Min and et al.}, year={2018}, month={Dec}, pages={1124–1138} }
 @article{morgan_chen_christopher_langstrom_wiggenhorn_getz_beresford_hoffelder_acerbi_andrews_et al._2018, title={Performance of the Population Bioequivalence (PBE) Statistical Test Using an IPAC-RS Database of Delivered Dose from Metered Dose Inhalers}, volume={19}, ISSN={["1530-9932"]}, DOI={10.1208/s12249-017-0941-8}, abstractNote={This article reports performance characteristics of the population bioequivalence (PBE) statistical test recommended by the US Food and Drug Administration (FDA) for orally inhaled products. A PBE Working Group of the International Pharmaceutical Aerosol Consortium on Regulation and Science (IPAC-RS) assembled and considered a database comprising delivered dose measurements from 856 individual batches across 20 metered dose inhaler products submitted by industry. A review of the industry dataset identified variability between batches and a systematic lifestage effect that was not included in the FDA-prescribed model for PBE. A simulation study was designed to understand PBE performance when factors identified in the industry database were present. Neglecting between-batch variability in the PBE model inflated errors in the equivalence conclusion: (i) The probability of incorrectly concluding equivalence (type I error) often exceeded 15% for non-zero between-batch variability, and (ii) the probability of incorrectly rejecting equivalence (type II error) for identical products approached 20% when product and between-batch variabilities were high. Neglecting a systematic through-life increase in the PBE model did not substantially impact PBE performance for the magnitude of lifestage effect considered. Extreme values were present in 80% of the industry products considered, with low-dose extremes having a larger impact on equivalence conclusions. The dataset did not support the need for log-transformation prior to analysis, as requested by FDA. Log-transformation resulted in equivalence conclusions that depended on the direction of product mean differences. These results highlight a need for further refinement of in vitro equivalence methodology.}, number={3}, journal={AAPS PHARMSCITECH}, author={Morgan, Beth and Chen, Stephanie and Christopher, David and Langstrom, Goran and Wiggenhorn, Christopher and Getz, Elise Burmeister and Beresford, Hayden and Hoffelder, Thomas and Acerbi, Daniela and Andrews, Stephen and et al.}, year={2018}, month={Apr}, pages={1410–1425} }