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Yan Ma, PhD

About Dr. Ma


Dr. Ma’s research interests in statistical methodology center on inference for instrument reliability and rater agreement, nonparametric estimation and inference, observational studies, causal inferences, meta-analysis, complex survey data analysis, longitudinal data analysis, and missing data problems. He has successfully developed U-statistics based non-parametric estimators for a series of correlation and agreement indices including kappa, concordance correlation coefficient, and Cronbach’s coefficient alpha.

Dr. Ma’s areas of applications include HIV/AIDS, psychiatry, orthopedics, and anesthesiology. He has been collaborating with investigators across the departments at the Hospital for Special Surgery, providing statistical consulting assistance in study design, grant proposal, and data analysis utilizing rigorous statistical methods. In particular, he is very interested in studying the outcomes associated with rare events such as perioperative death and other complications following orthopedic surgery using large national database such as the National Health and Nutrition Examination Survey (NHANES) and the Nationwide Inpatient Sample (NIS).

Dr. Ma is statistical editor for Aesthetic Plastic Surgery and reviewer for Biostatistics, CHEST, Journal of Bone and Joint Surgery, Journal of Applied Statistics, Journal of Orthopedic Research, Psychology and Aging, and Statistics in Medicine.



Assistant Scientist, Hospital for Special Surgery
Assistant Professor of Biostatistics, Department of Public Health, Weill Cornell Medical College



Publications by Dr. Ma

Selected Publications

Ma Y, Tang W, Feng C, Tu XM. (2008). Inference for kappas for longitudinal study data: applications to sexual health research. Biometrics, 64: 781-789.

Ma Y, Tang W, Yu Q, Tu XM. (2009). Modeling concordance correlation coefficient for longitudinal data. Psychometrika, 75: 99-119.

Memtsoudis SG, Ma Y, González Della Valle A, Mazumdar M, Gaber-Baylis LK, MacKenzie CR, Sculco TP (2009): Perioperative outcomes after unilateral and bilateral total knee arthroplasty. Anesthesiology, 111:1206-16.  Accompanied by editorial: Perioperative Comparative Effectiveness Research, Anesthesiology, 111: 1180-2

Marawar S, Girardi FP, Sama AA, Ma Y, Gaber LK, Besculides MC, Memtsoudis SG. (2009). National trends in anterior cervical fusion procedures. (In press in Spine)

Ma Y, Gonzalez Della Valle A, Zhang H, Tu, X.M. (2010). A U-statistics based  approach for modeling cronbach coefficient alpha within a longitudinal data setting.  Statistics in Medicine; 29: 65-670.

Weskamp G, Mendelson K, Swendeman S, Le Gall S, Ma Y, Lyman S, Hinoki A, Eguchi S, Guaiquil V, Horiuchi K, Blobel CP. Pathological neovascularization is reduced by inactivation of ADAM17 in endothelial cells, but not in pericytes.  Circulation Research, 2010; 106:932-940

Brophy RH, Backus SI, Kraszewski AP, Steele BC, Ma Y, Osei D, Williams RJ. (2010). Gender differences in lower extremity alignment and muscle activation during the soccer kick. (In press in Journal of Bone and Joint Surgery)

Memtsoudis SG, Ma Y, Chiu YL, Walz JM, Voswinckel R, Mazumdar M. (2010). Perioperative mortality in patients with pulmonary hypertension undergoing major joint replacement. (In press in Anesthesia & Analgesia

For more publications, please see the PubMed listing.

Industry Relationships

Industry Relationships

One of the goals of HSS is to advance the science of orthopedic surgery, rheumatology, and related disciplines for the benefit of patients. Research staff at HSS may collaborate with outside companies for education, research and medical advances. HSS supports this collaboration in order to foster medical breakthroughs; however, HSS also believes that these collaborations must be disclosed.

As part of the disclosure process, this website lists Research staff collaborations with outside companies if the Research staff member received any payment during the prior year or expects to receive any payment in the next year. The disclosures are based on information provided by the Research staff and other sources and are updated regularly. Current ownership interests and leadership positions are also listed. Further information may be available on individual company websites.

As of March 04, 2014, Dr. Ma reported no relationships with healthcare industry.

By disclosing the collaborations of HSS Research staff with industry on this website, HSS and its Research staff make this information available to patients and the public, thus creating a transparent environment for those who are interested in this information. Further, the HSS Conflicts of Interest Policy does not permit payment of royalties on products developed by him/her that are used on patients at HSS.

Dr. Ma in the News