1
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Lipkovich I, Svensson D, Ratitch B, Dmitrienko A. Modern approaches for evaluating treatment effect heterogeneity from clinical trials and observational data. Stat Med 2024. [PMID: 39054669 DOI: 10.1002/sim.10167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 05/28/2024] [Accepted: 06/21/2024] [Indexed: 07/27/2024]
Abstract
In this paper, we review recent advances in statistical methods for the evaluation of the heterogeneity of treatment effects (HTE), including subgroup identification and estimation of individualized treatment regimens, from randomized clinical trials and observational studies. We identify several types of approaches using the features introduced in Lipkovich et al (Stat Med 2017;36: 136-196) that distinguish the recommended principled methods from basic methods for HTE evaluation that typically rely on rules of thumb and general guidelines (the methods are often referred to as common practices). We discuss the advantages and disadvantages of various principled methods as well as common measures for evaluating their performance. We use simulated data and a case study based on a historical clinical trial to illustrate several new approaches to HTE evaluation.
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Affiliation(s)
- Ilya Lipkovich
- Advanced Analytics and Access Capabilities, Eli Lilly and Company, Indianapolis, Indiana, USA
| | - David Svensson
- Statistical Innovation, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Bohdana Ratitch
- Clinical Statistics and Analytics, Research & Development, Pharmaceuticals, Bayer Inc., Mississauga, Ontario, Canada
| | - Alex Dmitrienko
- Department of Biostatistics, Mediana, San Juan, Puerto Rico, USA
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2
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Nestler S, Salditt M. Comparing type 1 and type 2 error rates of different tests for heterogeneous treatment effects. Behav Res Methods 2024:10.3758/s13428-024-02371-x. [PMID: 38509268 DOI: 10.3758/s13428-024-02371-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/13/2024] [Indexed: 03/22/2024]
Abstract
Psychologists are increasingly interested in whether treatment effects vary in randomized controlled trials. A number of tests have been proposed in the causal inference literature to test for such heterogeneity, which differ in the sample statistic they use (either using the variance terms of the experimental and control group, their empirical distribution functions, or specific quantiles), and in whether they make distributional assumptions or are based on a Fisher randomization procedure. In this manuscript, we present the results of a simulation study in which we examine the performance of the different tests while varying the amount of treatment effect heterogeneity, the type of underlying distribution, the sample size, and whether an additional covariate is considered. Altogether, our results suggest that researchers should use a randomization test to optimally control for type 1 errors. Furthermore, all tests studied are associated with low power in case of small and moderate samples even when the heterogeneity of the treatment effect is substantial. This suggests that current tests for treatment effect heterogeneity require much larger samples than those collected in current research.
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Affiliation(s)
- Steffen Nestler
- University of Münster, Institut für Psychologie, Fliednerstr. 21, 48149, Münster, Germany.
| | - Marie Salditt
- University of Münster, Institut für Psychologie, Fliednerstr. 21, 48149, Münster, Germany
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3
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Liu Z, Wang X. Model-based adaptive randomization procedures for heteroscedasticity of treatment responses. Stat Methods Med Res 2023; 32:1361-1376. [PMID: 37165894 DOI: 10.1177/09622802231173050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In clinical trials, the responses of patients usually depend on the assigned treatment as well as some important covariates, which may cause heteroscedasticity in treatment responses. As clinical trials are generally designed to demonstrate efficacy for the overall population, they are usually not adequately powered for detecting interactions. To improve the power of interaction tests, this article develops two model-based adaptive randomization procedures for heteroscedasticity of treatment responses, and derives their limiting allocation proportions, which are generalizations of the Neyman allocation. Issues of hypothesis testing and sample size estimation are also addressed. Simulation studies show that compared with complete randomization, the two model-based randomization procedures have greater power to detect differences in systematic effects, main treatment effects and treatment-covariate interactions. In addition, the validity of limiting allocation proportion is also verified through simulations.
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Affiliation(s)
- Zhongqiang Liu
- School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, China
| | - Xi Wang
- School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, China
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4
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Zhang B, Heng S, Ye T, Small DS. Social distancing and COVID-19: Randomization inference for a structured dose-response relationship. Ann Appl Stat 2023. [DOI: 10.1214/22-aoas1613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Bo Zhang
- Department of Statistics and Data Science, The Wharton School, University of Pennsylvania
| | - Siyu Heng
- Graduate Group in Applied Mathematics and Computational Science, School of Arts and Sciences, University of Pennsylvania
| | - Ting Ye
- Department of Biostatistics, University of Washington
| | - Dylan S. Small
- Department of Statistics and Data Science, The Wharton School, University of Pennsylvania
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5
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Zhang B, Mackay EJ, Baiocchi M. Statistical matching and subclassification with a continuous dose: Characterization, algorithm, and application to a health outcomes study. Ann Appl Stat 2023. [DOI: 10.1214/22-aoas1635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Bo Zhang
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center
| | - Emily J. Mackay
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania
| | - Mike Baiocchi
- Department of Epidemiology and Population Health, Stanford University
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6
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Chén OY, Phan H, Cao H, Qian T, Nagels G, de Vos M. Probing potential priming: Defining, quantifying, and testing the causal priming effect using the potential outcomes framework. Front Psychol 2022; 13:724498. [PMID: 36438320 PMCID: PMC9693796 DOI: 10.3389/fpsyg.2022.724498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 09/13/2022] [Indexed: 03/03/2024] Open
Abstract
Having previously seen an item helps uncover the item another time, given a perceptual or cognitive cue. Oftentimes, however, it may be difficult to quantify or test the existence and size of a perceptual or cognitive effect, in general, and a priming effect, in particular. This is because to examine the existence of and quantify the effect, one needs to compare two outcomes: the outcome had one previously seen the item vs. the outcome had one not seen the item. But only one of the two outcomes is observable. Here, we argue that the potential outcomes framework is useful to define, quantify, and test the causal priming effect. To demonstrate its efficacy, we apply the framework to study the priming effect using data from a between-subjects study involving English word identification. In addition, we show that what has been used intuitively by experimentalists to assess the priming effect in the past has a sound mathematical foundation. Finally, we examine the links between the proposed method in studying priming and the multinomial processing tree (MPT) model, and how to extend the method to study experimental paradigms involving exclusion and inclusion instructional conditions.
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Affiliation(s)
- Oliver Y. Chén
- Faculty of Social Sciences and Law, University of Bristol, Bristol, United Kingdom
| | - Huy Phan
- School of Electronic Engineering and Computer Science, Queen Mary University of London, London, United Kingdom
- The Alan Turing Institute, London, United Kingdom
| | - Hengyi Cao
- Department of Psychology, Yale University, New Haven, CT, United States
- Center for Psychiatric Neuroscience, Feinstein Institutes for Medical Research, Manhasset, NY, United States
- Division of Psychiatry Research, Zucker Hillside Hospital, Glen Oaks, NY, United States
| | - Tianchen Qian
- Donald Bren School of Information and Computer Sciences, University of California, Irvine, Irvine, CA, United States
| | - Guy Nagels
- Department of Neurology, Universitair Ziekenhuis Brussel, Jette, Belgium
- Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom
| | - Maarten de Vos
- Faculty of Engineering Science, KU Leuven, Leuven, Belgium
- Faculty of Medicine, KU Leuven, Leuven, Belgium
- KU Leuven Institute for Artificial Intelligence, Leuven, Belgium
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7
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Lee SY, Kim R, Rodgers J, Subramanian SV. Assessment of the predictive power of a causal variable: An application to the Head Start impact study. SSM Popul Health 2022; 19:101223. [PMID: 36124257 PMCID: PMC9482140 DOI: 10.1016/j.ssmph.2022.101223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 08/17/2022] [Accepted: 08/30/2022] [Indexed: 12/02/2022] Open
Abstract
In a study attempting to estimate a causal effect of a causal variable, an assessment of the predictive power of the causal variable can shed light on the heterogeneity around its average effect. Using data from the Head Start Impact Study, a randomized controlled trial of the Head Start, a nation-wide early childhood education program in the United States, we provide a parallel comparison between measures of average effect and predictive power of the Head Start on five cognitive outcomes. We observed that one year of the Head Start increased scores for all five outcomes, with effect sizes ranging from 0.12 to 0.19 standard deviations. Percent variation explained by the Head Start ranged from 0.56 to 1.62%. For binary versions of the outcomes, the overall pattern remained; the Head Start on average improved the outcomes by meaningful magnitudes. In contrast, in a fully adjusted model, the Head Start only improved area under the curve (AUC) by less than 1% and its influence on the variance of predicted probabilities was negligible. The Head-Start-only model only achieved AUC ranging from 50.22 to 55.24%. Negligible predictive power despite the significant average effect suggests that the heterogeneity in effects may be large. The average effect estimates may not generalize well to different populations or different Head Start program settings. Assessment of the predictive power of a causal variable in randomized data should be a routine practice as it can provide helpful information on the causal effect and especially its heterogeneity. The average effect and predictive power of Head Start were assessed. Head Start increased scores for five cognitive outcomes with effect sizes ranging from 0.12 to 0.19 standard deviations. Head Start only explained less than 2% of the child-level variance in cognitive outcomes. Head Start only achieved about 50% in AUC and improved less than 1% in AUC when added to a full model. The impact of Head Start is meaningfully sized on average but the effect heterogeneity is large.
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Affiliation(s)
- Sun Yeop Lee
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Rockli Kim
- Division of Health Policy and Management, College of Health Science, Korea University, Seoul, South Korea.,Interdisciplinary Program in Precision Public Health, Department of Public Health Sciences, Graduate School of Korea University, Seoul, South Korea
| | - Justin Rodgers
- Harvard Center for Population & Development Studies, Cambridge, MA, USA
| | - S V Subramanian
- Harvard Center for Population & Development Studies, Cambridge, MA, USA.,Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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8
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Dai M, Shen W, Stern HS. Nonparametric tests for treatment effect heterogeneity in observational studies. CAN J STAT 2022. [DOI: 10.1002/cjs.11728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Maozhu Dai
- Department of Statistics University of California Irvine California USA
| | - Weining Shen
- Department of Statistics University of California Irvine California USA
| | - Hal S. Stern
- Department of Statistics University of California Irvine California USA
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9
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Lee SY, Kim R, Rodgers J, Subramanian SV. Assessment of heterogeneous Head Start treatment effects on cognitive and social-emotional outcomes. Sci Rep 2022; 12:6411. [PMID: 35440710 PMCID: PMC9018838 DOI: 10.1038/s41598-022-10192-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 03/28/2022] [Indexed: 12/02/2022] Open
Abstract
Head Start is a federally funded, nation-wide program in the U.S. for enhancing school readiness of children aged 3–5 from low-income families. Understanding heterogeneity in treatment effects (HTE) is an important task when evaluating programs, but most attempts to explore HTE in Head Start have been limited to subgroup analyses that rely on average treatment effects by subgroups. This study applies an extension of multilevel modelling, complex variance modelling, to data from a randomized controlled trial of Head Start, Head Start Impact Study (HSIS). The treatment effects on the variance, in addition to the mean, of nine cognitive and social-emotional outcomes were assessed for 4,442 children aged 3–4 years who were followed until their 3rd grade year. Head Start had positive short-term effects on the means of multiple cognitive outcomes while having no effect on the means of social-emotional outcomes. Head Start reduced the variances of multiple cognitive and one social-emotional outcomes, meaning that substantial HTE exists. In particular, the increased mean and decreased variance reflect the ability of Head Start to improve the outcomes and reduce their variability. Exploratory secondary analyses suggested that larger benefits for children with Spanish as a primary language and low parental educational level partly explained the reduced variability, but the HTE remained and the variability was reduced even within these subgroups. Routinely monitoring the treatment effects on the variance, in addition to the mean, would lead to a more comprehensive program evaluation that describes how a program performs on average and on the entire distribution.
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Affiliation(s)
- Sun Yeop Lee
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Rockli Kim
- Division of Health Policy and Management, College of Health Sciences, Korea University, Seoul, South Korea. .,Interdisciplinary Program in Precision Public Health, Department of Public Health Sciences, Graduate School of Korea University, Seoul, South Korea. .,Harvard Center for Population and Development Studies, Cambridge, MA, USA.
| | - Justin Rodgers
- Harvard Center for Population and Development Studies, Cambridge, MA, USA
| | - S V Subramanian
- Harvard Center for Population and Development Studies, Cambridge, MA, USA.,Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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10
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Chen A, Au TC. Robust causal inference for incremental return on ad spend with randomized paired geo experiments. Ann Appl Stat 2022. [DOI: 10.1214/21-aoas1493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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11
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Affiliation(s)
- Maozhu Dai
- Department of Statistics, University of California – Irvine, Irvine, CA, USA
| | - Hal S. Stern
- Department of Statistics, University of California – Irvine, Irvine, CA, USA
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12
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Li Z, Li X, Yi X, Li T, Huang X, Ren X, Ma T, Li K, Guo H, Chen S, Ma Y, Shang L, Song B, Hu D. Characteristics, Prognosis, and Competing Risk Nomograms of Cutaneous Malignant Melanoma: Evidence for Pigmentary Disorders. Front Oncol 2022; 12:838840. [PMID: 35719966 PMCID: PMC9198425 DOI: 10.3389/fonc.2022.838840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 04/08/2022] [Indexed: 11/13/2022] Open
Abstract
PURPOSE Cutaneous malignant melanoma (CMM) always presents as a complex disease process with poor prognosis. The objective of the present study was to explore the influence of solitary or multiple cancers on the prognosis of patients with CMM to better understand the landscape of CMM. METHODS We reviewed the records of CMM patients between 2004 and 2015 from the Surveillance, Epidemiology, and End Results Program. The cumulative incidence function was used to represent the probabilities of death. A novel causal inference method was leveraged to explore the risk difference to death between different types of CMM, and nomograms were built based on competing risk models. RESULTS The analysis cohort contained 165,043 patients with CMM as the first primary malignancy. Patients with recurrent CMM and multiple primary tumors had similar overall survival status (p = 0.064), while their demographics and cause-specific death demonstrated different characteristics than those of patients with solitary CMM (p < 0.001), whose mean survival times are 75.4 and 77.3 months and 66.2 months, respectively. Causal inference was further applied to unveil the risk difference of solitary and multiple tumors in subgroups, which was significantly different from the total population (p < 0.05), and vulnerable groups with high risk of death were identified. The established competing risk nomograms had a concordance index >0.6 on predicting the probabilities of death of CMM or other cancers individually across types of CMM. CONCLUSION Patients with different types of CMM had different prognostic characteristics and different risk of cause-specific death. The results of this study are of great significance in identifying the high risk of cause-specific death, enabling targeted intervention in the early period at both the population and individual levels.
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Affiliation(s)
- Zichao Li
- Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- Department of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, China
| | - Xinrui Li
- Department of Health Statistics, School of Public Health, Fourth Military Medical University, Xi’an, China
| | - Xiaowei Yi
- West China School of Public Health and West China Fourth Hospital, Sichuan University, Chengdu, China
| | - Tian Li
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Xingning Huang
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Xiaoya Ren
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Tianyuan Ma
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Kun Li
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Hanfeng Guo
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Shengxiu Chen
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Yao Ma
- College of Basic Medicine, Fourth Military Medical University, Xi’an, China
| | - Lei Shang
- Department of Health Statistics, School of Public Health, Fourth Military Medical University, Xi’an, China
- *Correspondence: Lei Shang, ; Baoqiang Song, ; Dahai Hu,
| | - Baoqiang Song
- Department of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- *Correspondence: Lei Shang, ; Baoqiang Song, ; Dahai Hu,
| | - Dahai Hu
- Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi’an, China
- *Correspondence: Lei Shang, ; Baoqiang Song, ; Dahai Hu,
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13
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Lee SY, Kim R, Rodgers J, Subramanian S. Treatment effect heterogeneity in the head start impact study: A systematic review of study characteristics and findings. SSM Popul Health 2021; 16:100916. [PMID: 34584935 PMCID: PMC8455360 DOI: 10.1016/j.ssmph.2021.100916] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 08/05/2021] [Accepted: 09/05/2021] [Indexed: 11/19/2022] Open
Abstract
There have been consistent efforts to assess treatment effect heterogeneity (TEH) of Head Start using the data from the Head Start Impact Study (HSIS), a randomized controlled trial of a federally funded child development program for a nationally representative sample of low-income parents and their 3- and 4-year-old children in the United States. Including 28 studies on TEH of Head Start, this review found that multiple high-risk subgroups (e.g., children with lower cognitive abilities, Spanish-speaking dual language learners) experienced larger gains across a range of developmental and parental outcomes, but mixed results for several subgroups. Most studies focused on subgroup analyses, cognitive and social-emotional outcomes, and short-term effects. Further studies on distributional effects, health and parental outcomes, and long-term effects are warranted. Finally, suggestions for future research on TEH of Head Start are discussed, which are applicable to other child development programs and policy evaluations.
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Affiliation(s)
- Sun Yeop Lee
- Department of Epidemiology, Harvard T.H. Chan School of Public Health Boston, MA, USA
| | - Rockli Kim
- Interdisciplinary Program in Precision Public Health, Department of Public Health Sciences, Graduate School of Korea University, Seoul, Republic of Korea
- Division of Health Policy and Management, College of Health Science, Korea University, Seoul, Republic of Korea
- Harvard Center for Population & Development Studies, Cambridge, MA, USA
| | - Justin Rodgers
- Harvard Center for Population & Development Studies, Cambridge, MA, USA
| | - S.V. Subramanian
- Harvard Center for Population & Development Studies, Cambridge, MA, USA
- Department of Social and Behavioral Sciences, Harvard T.H. Chan School of Public Health, Boston, MA, USA
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14
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Puelz D, Basse G, Feller A, Toulis P. A graph‐theoretic approach to randomization tests of causal effects under general interference. J R Stat Soc Series B Stat Methodol 2021. [DOI: 10.1111/rssb.12478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David Puelz
- McCombs School of Business and Salem Center for Policy The University of Texas at Austin Austin Texas USA
| | | | - Avi Feller
- The University of California Berkeley California USA
| | - Panos Toulis
- Booth School of Business The University of Chicago Chicago Illinois USA
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15
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Wang W, Xu J, Schwartz J, Baccarelli A, Liu Z. Causal mediation analysis with latent subgroups. Stat Med 2021; 40:5628-5641. [PMID: 34263963 DOI: 10.1002/sim.9144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 05/13/2021] [Accepted: 07/01/2021] [Indexed: 01/29/2023]
Abstract
In biomedical studies, the causal mediation effect might be heterogeneous across individuals in the study population due to each study subject's unique characteristics. While individuals' mediation effects may differ from each other, it is often reasonable and more interpretable to assume that individuals belong to several distinct latent subgroups with similar attributes. In this article, we first show that the subgroup-specific mediation effect can be identified under the group-specific sequential ignorability assumptions. Then, we propose a simple mixture modeling approach to account for the latent subgroup structure where each mixture component corresponds to one latent subgroup in the linear structural equation model framework. Model parameters can be estimated using the standard expectation-maximization (EM) algorithm. Each individual's subgroup membership can be inferred based on the posterior probability. We propose to use the singular Bayesian information criterion to consistently select the number of latent subgroups by recognizing that the Fisher information matrix for mixture models might be singular. We then propose to use nonparametric bootstrap method to compute standard errors and confidence intervals. We conducted simulation studies to evaluate the empirical performance of our proposed method named iMed. Finally, we reanalyzed a DNA methylation data set from the Normative Aging Study and found that the mediation effects of two well-documented DNA methylation CpG sites are heterogeneous across two latent subgroups in the causal pathway from smoking behavior to lung function. We also developed an R package iMed for public use.
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Affiliation(s)
- WenWu Wang
- School of Statistics, Qufu Normal University, Shandong, China
| | - Jinfeng Xu
- Department of Statistics and Actuarial Science, University of Hong Kong, Pokfulam, Hong Kong SAR, China
| | - Joel Schwartz
- Department of Environmental Health, Harvard University, Boston, Massachusetts, USA
| | - Andrea Baccarelli
- Department of Environmental Health Sciences, Columbia University, New York, New York, USA
| | - Zhonghua Liu
- Department of Statistics and Actuarial Science, University of Hong Kong, Pokfulam, Hong Kong SAR, China
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16
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Branson Z, Shao S. Ridge rerandomization: An experimental design strategy in the presence of covariate collinearity. J Stat Plan Inference 2021. [DOI: 10.1016/j.jspi.2020.07.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Affiliation(s)
- Jason Wu
- Department of Statistics, University of California, Berkeley, CA
| | - Peng Ding
- Department of Statistics, University of California, Berkeley, CA
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18
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Branson Z, Dasgupta T. Sampling‐based Randomised Designs for Causal Inference under the Potential Outcomes Framework. Int Stat Rev 2019. [DOI: 10.1111/insr.12339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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19
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Ding P, Keele L. Rank tests in unmatched clustered randomized trials applied to a study of teacher training. Ann Appl Stat 2018. [DOI: 10.1214/18-aoas1147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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20
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Fogarty CB. On mitigating the analytical limitations of finely stratified experiments. J R Stat Soc Series B Stat Methodol 2018. [DOI: 10.1111/rssb.12290] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Affiliation(s)
- Peng Ding
- Department of Statistics, University of California, Berkeley, CA
| | - Avi Feller
- Department of Statistics, University of California, Berkeley, CA
- Goldman School of Public Policy, University of California, Berkeley, CA
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22
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Affiliation(s)
- Weihua An
- Department of Sociology and Institute for Quantitative Theory and Methods, Emory University, Atlanta, GA
| | - Ying Ding
- School of Informatics and Computing, Indiana University, IN
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23
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Fay MP, Brittain EH, Shih JH, Follmann DA, Gabriel EE. Causal estimands and confidence intervals associated with Wilcoxon-Mann-Whitney tests in randomized experiments. Stat Med 2018; 37:2923-2937. [PMID: 29774591 PMCID: PMC6373726 DOI: 10.1002/sim.7799] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 03/05/2018] [Accepted: 04/03/2018] [Indexed: 11/10/2022]
Abstract
Although the P value from a Wilcoxon-Mann-Whitney test is used often with randomized experiments, it is rarely accompanied with a causal effect estimate and its confidence interval. The natural parameter for the Wilcoxon-Mann-Whitney test is the Mann-Whitney parameter, ϕ, which measures the probability that a randomly selected individual in the treatment arm will have a larger response than a randomly selected individual in the control arm (plus an adjustment for ties). We show that the Mann-Whitney parameter may be framed as a causal parameter and show that it is not equal to a closely related and nonidentifiable causal effect, ψ, the probability that a randomly selected individual will have a larger response under treatment than under control (plus an adjustment for ties). We review the paradox, first expressed by Hand, that the ψ parameter may imply that the treatment is worse (or better) than control, while the Mann-Whitney parameter shows the opposite. Unlike the Mann-Whitney parameter, ψ is nonidentifiable from a randomized experiment. We review some nonparametric assumptions that rule out Hand's paradox through bounds on ψ and use bootstrap methods to make inferences on those bounds. We explore the relationship of the proportional odds parameter to Hand's paradox, showing that the paradox may occur for proportional odds parameters between 1/9 and 9. Thus, large effects are needed to ensure that if treatment appears better by the Mann-Whitney parameter, then treatment improves responses in most individuals. We demonstrate these issues using a vaccine trial.
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Affiliation(s)
- Michael P Fay
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Erica H Brittain
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Joanna H Shih
- Biometric Research Branch, DCTD, National Cancer Institute, Rockville, MD, USA
| | - Dean A Follmann
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Erin E Gabriel
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden
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Ding P, Dasgupta T. A randomization-based perspective on analysis of variance: a test statistic robust to treatment effect heterogeneity. Biometrika 2017. [DOI: 10.1093/biomet/asx059] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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