Alex Levis
About Research Teaching Posts CV
Alex Levis

Research Areas and Selected Publications

Statistical Methodology & Theory

Instrumental Variables

  • Levis, A.W., Bonvini, M.*, Zeng*, Z., Keele, L., Kennedy, E.H. “Covariate-assisted bounds on causal effects with instrumental variables.” arXiv:2301.12106. Under revision for the Journal of the Royal Statistical Society: Series B.

  • Levis, A.W., Kennedy, E.H., Keele, L. “Nonparametric identification and efficient estimation of causal effects with instrumental variables.” arXiv:2402.09332. Submitted to Statistical Science.

  • Rakshit, P., Levis, A.W., Keele, L. “Local effects of continuous instruments without positivity.” arXiv:2409.07350. Submitted to the Journal of the Royal Statistical Society: Series B.

  • Takatsu, K., Levis, A.W., Kennedy, E.H., Kelz, R., Keele, L, 2024. “Doubly-robust machine learning-based estimation methods for instrumental variables with an application to surgical care for cholecystitis.” arXiv:2307.06269. Journal of the Royal Statistical Society: Series A, p. qnae089. doi:10.1093/jrsssa/qnae089.

Missing data

  • Levis, A.W., Mukherjee, R., Wang, R., Haneuse, S. “Double sampling and semiparametric methods for data missing not at random.” arXiv:2204.02432. Under revision at Statistics in Medicine.

  • Sun, S., Haneuse, S., Levis, A.W., Lee, C., et al. “Causal quantile treatment effects with missing data by double-sampling.” arXiv:2310.09239. Under revision at Biometrics.

  • Levis, A.W., Mukherjee, R., Wang, R., Haneuse, S, 2024. “Robust causal inference for point exposures with missing confounders.” Canadian Journal of Statistics, p. e11832. doi:10.1002/cjs.11832.

  • Benz, L., Levis, A.W., Haneuse, S. “Comparing causal inference methods for point exposures with missing confounders: a simulation study.” arXiv:2407.06038. Submitted to BMC Medical Research Methodology.

Transportability and Multi-Source Estimation

  • Liu, Y., Levis, A.W., Normand, S. -L., Han, L, 2024. “Multi-source conformal inference under distribution shift.” arXiv:2405.09331. Proceedings of the 41-st International Conference on Machine Learning. PMLR 235:31344-31382.

  • Wang, G., Levis, A.W., Steingrimsson, J.A., Dahabreh, I.J. “Efficient estimation of subgroup treatment effects using multi-source data.” arXiv:2402.02684.

  • Wang, G., Levis, A.W., Steingrimsson, J.A., Dahabreh, I.J. “Causal inference under transportability assumptions for conditional relative effect measures.” arXiv:2402.02702.

Effect Estimation in Longitudinal Studies

  • Loewinger, G.*, Levis, A.W.*, Pereira, F. “Nonparametric causal inference for optogenetics: sequential excursion effects for dynamic regimes.” arXiv:2405:18597. Submitted to the Journal of the American Statistical Association.

  • Levis, A.W.*, Loewinger, G.*, Pereira, F. “Causal inference in the closed-loop: marginal structural models for sequential excursion effects.” arXiv:2405:18597v1. Accepted to NeurIPS, 2024.

Optimal Policies

  • Levis, A.W., Ben-Michael, E., Kennedy, E.H. “Intervention effects based on potential benefit.” arXiv:2405.08727. Submitted to the Annals of Statistics.

Applied Research

Electronic Health Records

  • Koffman, L., Levis, A.W., Haneuse, S., Johnson, E., et al., 2021. “Evaluation of intensive telephonic nutritional and lifestyle counseling to enhance outcomes of bariatric surgery.” Obesity Surgery, 32, p. 133-141. doi:10.1007/s11695-021-05749-4.

  • Koffman, L., Levis, A.W., Arterburn, D., Coleman, K.J., et al., 2021. “Investigating bias from missing data in an electronic health records-based study of weight loss after bariatric surgery.” Obesity Surgery, 31, p. 2125-2135. doi:10.1007/s11695-021-05226-y.

Metascience

  • Thombs, B.D., Levis, A.W., Azar, M., Saadat, N., et al., 2020. “Group sample sizes in nonregulated health care intervention trials described as randomized controlled trials were overly similar.” Journal of Clinical Epidemiology, 120, p. 8-16. doi:10.1016/j.jclinepi.2019.12.011.

  • Thombs, B.D., Kwakkenbos, L., Levis, A.W., Benedetti, A., 2018. “Addressing overestimation of the prevalence of depression based on self-report screening questionnaires.” Canadian Medical Association Journal, 190, p. E44-E49. doi:10.1503/cmaj.170691.

  • Coronado-Montoya, S., Levis, A.W., Kwakkenbos, L., Steele, R.J., et al., 2016. “Reporting of positive results in randomized controlled trials of mindfulness-based mental health interventions.” PloS One, 11(4):e0153220. doi:10.1371/journal.pone.0153220.

  • Levis, A.W., Leentjens, A.F., Levenson, J.L., Lumley, M.A., et al., 2015. “Comparison of self-citation by peer reviewers in a journal with single-blind peer review versus a journal with open peer review.” Journal of Psychosomatic Research, 79(6), p. 561-565. doi:10.1016/j.jpsychores.2015.08.004.

  • Thombs, B.D., Levis, A.W., Razykov, I., Syamchandra, A., et al., 2015. “Potentially coercive self-citation by peer reviewers: a cross-sectional study.” Journal of Psychosomatic Research, 78(1), p. 1-6. doi:10.1016/j.jpsychores.2014.09.015.

Item Response Theory

  • Harel, D., Levis, B., Ishihara, M., Levis, A.W., et al., 2021. “Shortening the Edinburgh postnatal depression scale using optimal test assembly methods: Development of the EPDS‐Dep‐5”. Acta Psychiatrica Scandinavica, 143(4), p. 348-362. doi:10.1111/acps.13272.

  • Ishihara, M., Harel, D., Levis, B., Levis, A.W., et al., 2019. “Shortening self‐report mental health symptom measures through optimal test assembly methods: Development and validation of the Patient Health Questionnaire‐Depression‐4.” Depression and Anxiety, 36(1), p. 82-92. doi:10.1002/da.22841.

  • Levis, A.W., Harel, D., Kwakkenbos, L., Carrier, M.E., et al., 2016. “Using optimal test assembly methods for shortening patient-reported outcome measures: Development and validation of the Cochin Hand Function Scale-6: A scleroderma patient-centered intervention network cohort study.” Arthritis Care & Research, 68(11), p. 1704-1713. doi:10.1002/acr.22893.

Systematic Reviews and Meta-analysis

  • Delisle, V.C., Gumuchian, S.T., Rice, D.B., Levis, A.W., et al., 2017. “Perceived benefits and factors that influence the ability to establish and maintain patient support groups in rare diseases: a scoping review.” The Patient-Patient-Centered Outcomes Research, 10, p. 283-293. doi:10.1007/s40271-016-0213-9.

  • Levis, B., Benedetti, A., Levis, A.W., Ioannidis, J.P., et al., 2017. “Selective cutoff reporting in studies of diagnostic test accuracy: a comparison of conventional and individual-patient-data meta-analyses of the Patient Health Questionnaire-9 depression screening tool.” Americal Journal of Epidemiology, 185(10), p. 954-964. doi:10.1093/aje/kww191.

Nutrition and Global Health

  • Golden, C.D., Zamborain-Mason, J., Levis, A., Rice, B.L., et al., 2024. “Prevalence of micronutrient deficiencies across diverse environments in rural Madagascar.” Frontiers in Nutrition, 11, p. 1389080. doi:10.3389/fnut.2024.1389080.

  • Truche, P., Botelho, F., Bowder, A.N., Levis, A.W., et al., 2021. “Potentially avertable child mortality associated with surgical workforce scale-up in low-and middle-income countries: a global study.” World Journal of Surgery, 45(9), p. 2643-2652. doi:10.1007/s00268-021-06181-6.

* Denotes equal author contribution