Articles
Predictive accuracy of risk factors and markers: a simulation study of the effect of novel markers on different performance measures for logistic regression models, Statistics in Medicine (2013)
The change in c-statistic is frequently used to summarize the change in predictive accuracy when...
Using methods from the data-mining and machine-learning literature for disease classification and prediction: a case study examining classification of heart failure subtypes, Journal of Clinical Epidemiology (2013)
OBJECTIVE: Physicians classify patients into those with or without a specific disease. Furthermore, there is...
Comparative ability of comorbidity classification methods for administrative data to predict outcomes in patients with chronic obstructive pulmonary disease, Annals of Epidemiology (2012)
PURPOSE: Administrative healthcare databases are used for health services research, comparative effectiveness studies, and measuring...
Comparing the cohort design and the nested case-control design in the presence of both time-invariant and time-dependent treatment and competing risks: bias and precision, Pharmacoepidemiology and Drug Safety (2012)
Purpose: Observational studies using electronic administrative health care databases are often used to estimate the...
Generating survival times to simulate Cox proportional hazards models with time-varying covariates., Statistics in Medicine (2012)
Simulations and Monte Carlo methods serve an important role in modern statistical research. They allow...
Interpreting the concordance statistic of a logistic regression model: relation to the variance and odds ratio of a continuous explanatory variable, BMC Medical Research Methodology (2012)
Background: When outcomes are binary, the c-statistic (equivalent to the area under the Receiver Operating...
Regression trees for predicting mortality in patients with cardiovascular disease: what improvement is achieved by using ensemble-based methods?, Biometrical Journal (2012)
In biomedical research, the logistic regression model is the most commonly used method for predicting...
Using Ensemble-Based Methods for Directly Estimating Causal Effects: An Investigation of Tree-Based G-Computation, Multivariate Behavioral Research (2012)
Researchers are increasingly using observational or nonrandomized data to estimate causal treatment effects. Essential to...
Using the Johns Hopkins Aggregated Diagnosis Groups (ADGs) to predict mortality in a population-based cohort of subjects with schizophrenia in Ontario, Canada, Psychiatry Research (2012)
Administrative health care databases are increasingly used for health services and comparative effectiveness research. When...
A Tutorial and Case Study in Propensity Score Analysis: An Application to Estimating the Effect of In-Hospital Smoking Cessation Counseling on Mortality, Multivariate Behavioral Research (2011)
Propensity score methods allow investigators to estimate causal treatment effects using observational or nonrandomized data....
A Tutorial on Methods to Estimating Clinically and Policy-Meaningful Measures of Treatment Effects in Prospective Observational Studies: A Review (with Andreas Laupacis), The International Journal of Biostatistics (2011)
In randomized controlled trials (RCTs), treatment assignment is unconfounded with baseline covariates, allowing outcomes to...
An introduction to propensity-score methods for reducing confounding in observational studies, Multivariate Behavioral Research (2011)
The propensity score is the probability of treatment assignment conditional on observed baseline characteristics. The...
Comparing paired vs. non-paired statistical methods of analyses when making inferences about absolute risk reductions in propensity-score matched samples., Statistics in Medicine (2011)
Propensity-score matching allows one to reduce the effects of treatment-selection bias or confounding when estimating...
Optimal caliper widths for propensity-score matching when estimating differences in means and differences in proportions in observational studies., Pharmaceutical Statistics (2011)
In a study comparing the effects of two treatments, the propensity score is the probability...
The Mortality Risk Score and the ADG Score: two points-based scoring systems for the Johns Hopkins Aggregated Diagnosis Groups (ADGs) to predict mortality in a general adult population cohort in Ontario, Canada, Medical Care (2011)
Background: Logistic regression models that incorporated age, sex, and indicator variables for the Johns Hopkins’...
Using the Johns Hopkins Aggregated Diagnosis Groups (ADGs) to predict mortality in a general adult population cohort in Ontario, Canada, Medical Care (2011)
Background: Administrative health care databases are increasingly used for health services and comparative effectiveness research....
Logistic regression had superior performance compared to regression trees for predicting in-hospital mortality in patients hospitalized with heart failure, Journal of Clinical Epidemiology (2010)
Objective: To compare the predictive accuracy of regression trees with that of the logistic regression...
A Comparison of the Statistical Power of Different Methods for the Analysis of Repeated Cross-Sectional Cluster Randomization Trials with Binary Outcomes, The International Journal of Biostatistics (2010)
Repeated cross-sectional cluster randomization trials are cluster randomization trials in which the response variable is...
Type I Error Rates, Coverage of Confidence Intervals, and Variance Estimation in Propensity-Score Matched Analyses, The International Journal of Biostatistics (2010)
Propensity-score matching is frequently used in the medical literature to reduce or eliminate the effect...
A data-generation process for data with specified risk differences or numbers needed to treat, Communications in Statistics - Simulation and Computation (2010)
Monte Carlo simulation methods are increasingly being used to evaluate the performance of statistical methods...
A substantial and confusing variation exists in handling of baseline covariates in randomized controlled trials: a review of trials published in leading medical journals., Journal of Clinical Epidemiology (2010)
Objective: Statisticians have criticized the use of significance testing to compare the distribution of baseline...
Absolute risk reductions and numbers needed to treat can be obtained from adjusted survival models for time-to-event outcomes, Journal of Clinical Epidemiology (2010)
Objective: Cox proportional hazards regression models are frequently used to determine the association between exposure...
Absolute risk reductions, relative risks, relative risk reductions, and numbers needed to treat can be obtained from a logistic regression model, Journal of Clinical Epidemiology (2010)
Objective: Logistic regression models are frequently used in cohort studies to determine the association between...
Estimating Multilevel Logistic Regression Models When the Number of Clusters is Low: A Comparison of Different Statistical Software Procedures, The International Journal of Biostatistics (2010)
Multilevel logistic regression models are increasingly being used to analyze clustered data in medical, public...
Statistical Criteria for Selecting the Optimal Number of Untreated Subjects Matched to Each Treated Subject When Using Many-to-One Matching on the Propensity Score, American Journal of Epidemiology (2010)
Propensity-score matching is increasingly being used to estimate the effects of treatments using observational data....
Survivor-treatment bias, treatment-selection bias, and propensity scores in observational research, Journal of Clinical Epidemiology (2010)
Commentary - no abstract available
The performance of different propensity-score methods for estimating differences in proportions (risk differences or absolute risk reductions) in observational studies, Statistics in Medicine (2010)
Propensity score methods are increasingly being used to estimate the effects of treatments on health...
Are (the log-odds of) Hospital Mortality Rates Normally Distributed in Ontario? Implications for Studying Variations in Outcomes of Medical Care, Journal of Evaluation in Clinical Practice (2009)
Objective: Hierarchical regression models are used to examine variations in outcomes following the provision of...
Balance diagnostics for comparing the distribution of baseline covariates between treatment groups in propensity-score matched samples, Statistics in Medicine (2009)
The propensity score is a subject’s probability of treatment, conditional on observed baseline covariates. Conditional...
Some Methods of Propensity-Score Matching had Superior Performance to Others: Results of an Empirical Investigation and Monte Carlo simulations, Biometrical Journal (2009)
Propensity-score matching is increasingly being used to reduce the impact of treatment-selection bias when estimating...
The concept of the marginal subject in propensity-score matched analyses (with Douglas S. Lee), Pharmacoepidemiology and Drug Safety (2009)
Propensity-score matching is increasingly being used to reduce the impact of treatment-selection bias when estimating...
The relative ability of different propensity-score methods to balance measured covariates between treated and untreated subjects in observational studies, Medical Decision Making (2009)
The propensity score is a balancing score: conditional on the propensity score, treated and untreated...
Using the standardized difference to compare the prevalence of a binary variable between two groups in observational research, Communications in Statistics – Simulation and Computation (2009)
Researchers are increasingly using the standardized difference to compare the distribution of baseline covariates between...
A critical appraisal of propensity score matching in the medical literature from 1996 to 2003, Statistics in Medicine (2008)
Propensity-score methods are increasingly being used to reduce the impact of treatment-selection bias in the...
A report card on propensity-score matching in the cardiology literature from 2004 to 2006: results of a systematic review, Circulation: Cardiovascular Quality and Outcomes (2008)
Background— Propensity-score matching is frequently used in the cardiology literature. Recent systematic reviews have found...
Assessing balance in baseline covariates when using many-to-one matching on the propensity-score, Pharmacoepidemiology and Drug Safety (2008)
The propensity score is defined to be a subject’s probability of treatment selection, conditional on...
Bayes Rules for Optimally using Hierarchical Regression Models to Identify High-mortality Hospitals, BMC Health Research Methodology (2008)
Background
There is a growing trend towards the production of "hospital report-cards" in which hospitals...
Bootstrap model selection had similar performance for selecting authentic and noise variables compared to backwards variable elimination: a simulation study, Journal of Clinical Epidemiology. (2008)
Objective Researchers have proposed using bootstrap resampling in conjunction with automated variable selection methods to...
Comparing clinical and administrative data for profiling hospitals on post-discharge medication use by AMI patients, American Heart Journal (2008)
Background
Postdischarge medication use is frequently used as a measure of hospital performance, with many...
Factors associated with the use of evidence-based therapies after discharge among elderly patients with myocardial infarction, Canadian Medical Association Journal (CMAJ) (2008)
Background: In an accompanying article, we report moderate between-hospital variation in the postdischarge use of...
Goodness-of-fit diagnostics for the propensity score model when estimating treatment effects using covariate adjustment with the propensity score, Pharmacoepidemiology and Drug Safety (2008)
The propensity score is defined to be a subject’s probability of treatment selection, conditional on...
Optimal Bayesian Probability Levels for Hospital Report Cards, Health Services and Outcomes Research Methodology (2008)
here is a growing trend towards the production of “hospital report-cards” in which hospitals with...
Pisces did not have increased heart failure: Data-driven comparisons of binary proportions between levels of a categorical variable can result in incorrect statistical significance level, Journal of Clinical Epidemiology (2008)
Objective We examined the impact on statistical inference when a χ2 test is used to...
R and S-PLUS produced different classification trees for predicting patient mortality, Journal of Clinical Epidemiology (2008)
Objective There is a growing interest in using classification and regression trees in biomedical research....
The large-sample performance of backwards variable elimination, Journal of Applied Statistics (2008)
Prior studies have shown that automated variable selection results in models with substantially inflated estimates...
The performance of different propensity score methods for estimating relative risks.., Journal of Clinical Epidemiology (2008)
Objectives The propensity score is the probability of treatment conditional on observed variables. Conditioning on...
The performance of two data-generation processes for data with specified marginal treatment odds ratios, Communications in Statistics – Simulation and Computation (2008)
Monte Carlo simulation methods are increasingly being used to evaluate the property of statistical estimators...
Use of evidence-based therapies after discharge among elderly patients with acute myocardial infarction, Canadian Medical Association Journal (CMAJ) (2008)
Background: Postdischarge use of evidence-based drug therapies has been proposed as a measure of quality...
Using the Bootstrap to improve estimation and confidence intervals for regression coefficients selected using backwards variable elimination, Statistics in Medicine (2008)
Applied researchers frequently use automated model selection methods, such as backwards variable elimination, to develop...
A comparison of classification and regression trees, logistic regression, generalized additive models, and multivariate adaptive regression splines for predicting AMI mortality, Statistics in Medicine (2007)
Clinicians and health service researchers are frequently interested in predicting patient-specific probabilities of adverse events...
A Comparison of the Ability of Different Propensity Score Models to Balance Measured Variables between Treated and Untreated Subjects: A Monte Carlo Study, Statistics in Medicine (2007)
The propensity score - the probability of exposure to a specific treatment conditional on observed...
A comparison of the statistical power of different methods for the analysis of cluster randomization trials with binary outcomes, Statistics in Medicine (2007)
Cluster randomization trials are randomized controlled trials (RCTs) in which intact clusters of subjects are...
Conditioning on the propensity score can result in biased estimation of common measures of treatment effect: A Monte Carlo study, Statistics in Medicine (2007)
Propensity score methods are increasingly being used to estimate causal treatment effects in the medical...
Propensity-score matching in the cardiovascular surgery literature from 2004 to 2006: A systematic review and suggestions for improvement, Journal of Thoracic and Cardiovascular Surgery. (2007)
Objective I conducted a systematic review of the use of propensity score matching in the...
The performance of different propensity score methods for estimating marginal odds ratios, Statistics in Medicine (2007)
The propensity score which is the probability of exposure to a specific treatment conditional on...
A Comparison of Propensity Score Methods: A Case-Study Estimating the Effectiveness of Post-AMI Statin Use, Statistics in Medicine (2006)
There is an increasing interest in the use of propensity score methods to estimate causal...
Comparing Clinical Data with Administrative Data for Producing AMI Report Cards, Journal of the Royal Statistical Society – Series A (Statistics in Society). (2006)
We compared measures of hospital performance by using both administrative and clinical data sources. Hospital-specific...
How many me-too drugs are enough? The case of physician preferences for specific statins, Annals of Pharmacotherapy (2006)
BACKGROUND: The increasing availability of "Me-Too" drugs has provided considerable treatment options for clinicians. However,...
Missed Opportunities in the Secondary Prevention of Myocardial Infarction: An Assessment of the Effects of Statin Underprescribing on Mortality, American Heart Journal (2006)
Background The benefits of statins for the secondary prevention of coronary heart disease are well...
Quantifying the Impact of Survivor Treatment Bias in Observational Studies, Journal of Evaluation in Clinical Practice (2006)
Rationale: Observational cohort studies are frequently used to measure the impact of therapies on the...
Testing Multiple Statistical Hypotheses Resulted in Spurious Associations: A Study of Astrological Signs and Health, Journal of Clinical Epidemiology (2006)
Objectives To illustrate how multiple hypotheses testing can produce associations with no clinical plausibility.
Study...
The Impact of Unmeasured Clinical Variables on the Accuracy of Hospital Report Cards: A Monte Carlo Study, Medical Decision Making (2006)
Purpose. Hospital report cards are commonly produced using administrative data. The objective of this study...
Bayesian Modeling of Missing Data in Clinical Research, Computational Statistics & Data Analysis (2005)
The issue of missing data frequently confronts researchers using data derived from patient medical records....
Bias in Penalized Quasi-Likelihood Estimation in Random Effects Logistic Regression Models when the Random Effects are not Normally Distributed, Communications in Statistics – Simulation and Computation (2005)
Regression models incorporating random effects are being used with increasing frequency to examine variations in...
Impact of the Pravastatin or Atorvastatin Evaluation and Infection Therapy-Thrombolysis In Myocardial Infarction 22/Reversal of Atherosclerosis With Aggressive Lipid Lowering Trials on Trends in Intensive Versus Moderate Statin Therapy in Ontario, Canada, Circulation (2005)
Background— In March 2004, the Reversal of Atherosclerosis With Aggressive Lipid Lowering (REVERSAL) trial demonstrated...
Optimal Statistical Decisions for Hospital Report Cards, Medical Decision Making (2005)
Purpose: Hospital report cards provide information designed to help patients and providers to make decisions....
The Impact of Under Coding of Cardiac Severity and Comorbid Diseases on the Accuracy of Hospital Report Cards, Medical Care (2005)
Context: Hospital report cards are usually based on administrative discharge abstracts. However, cardiac severity and...
The Reliability and Validity of Bayesian Methods for Hospital Profiling: A Monte Carlo Assessment, Journal of Statistical Planning and Inference (2005)
There is a growing trend towards the production of “hospital report-cards” in which hospitals with...
The Use of Quantile Regression in Health Care Research: A Case Study Examining Gender Differences in the Delivery of Thrombolysis, Statistics in Medicine (2005)
Investigators are frequently interested in determining patient and system characteristics associated with delays in the...
The Use of the Propensity Score for Estimating Treatment Effects: Administrative versus Clinical Data, Statistics in Medicine (2005)
There is an increasing interest in using administrative data to estimate the treatment effects of...
Automated variable selection methods for logistic regression produced unstable models for predicting acute myocardial infarction mortality, Journal of Clinical Epidemiology (2004)
Objectives Automated variable selection methods are frequently used to determine the independent predictors of an...
Bootstrap Methods for Developing Predictive Models in Cardiovascular Research, The American Statistician (2004)
Researchers frequently use automated model selection methods such as backwards elimination to identify variables that...
Changes in Prescribing Patterns Following Publication of the ALLHAT Trial, Journal of the American Medical Association (2004)
Estimating linear regression models in the presence of a censored independent variable, Statistics in Medicine (2004)
The current study examined the impact of a censored independent variable, after adjusting for a...
Inflation of the Type I Error Rate When a Continuous Confounding Variable is Categorized in Logistic Regression Analyses, Statistics in Medicine (2004)
This paper demonstrates an inflation of the type I error rate that occurs when testing...
The Impact of the Choice of Benchmark on the Conclusions of Hospital Report Cards, American Heart Journal (2004)
Abstract Background Hospital report cards for outcomes following acute myocardial infarction (AMI) are being produced...
Trends in Use of Clonidine in Ontario Canada, Following Publication of the Women’s Health Initiative Study, Canadian Journal of Clinical Pharmacology (2004)
Background: Following publication of the Women’s Health Initiative (WHI) study, many women discontinued use of...
A Comparison of Several Regression Models for Analyzing Cost of CABG Surgery, Statistics in Medicine (2003)
Investigators in clinical research are often interested in determining the association between patient characteristics and...
Anxiety-related visits to physicians following September 11, 2001 in Ontario, Canada, Canadian Journal of Psychiatry (2003)
Comparing hierarchical modeling with traditional logistic regression analysis among patients hospitalized with acute myocardial infarction: Should we be analyzing cardiovascular outcomes data differently?, American Heart Journal (2003)
Background: Data in health research are frequently structured hierarchically. For example, data may consist of...
Prescriptions for Estrogen Replacement Therapy in Ontario Before and After Publication of the Women’s Health Initiative Study, Journal of the American Medical Association. (2003)
Quantile Regression: A Statistical Tool for Out-of-hospital Research, Academic Emergency Medicine (2003)
The Accuracy of Fixed and Random Effects Models for Classifying Hospitals as Mortality Outliers: A Monte Carlo Assessment, Medical Decision Making (2003)
Background. There is an increasing movement towards the release of hospital "report-cards." However, there is...
The Use of Finite Mixture Models to Estimate the Distribution of the Health Utilities Index in the Presence of a Ceiling Effect, Journal of Applied Statistics (2003)
Finite mixture models are flexible parametric models that allow one to describe complex probability distributions...
Type I Error Inflation in the Presence of a Ceiling Effect, The American Statistician (2003)
Many variables in biomedical research (e.g., indices of health status) are measured with ceiling effects,...
A Brief Note on Overlapping Confidence Intervals, Journal of Vascular Surgery (2002)
Clinical researchers frequently assess the statistical significance of the difference between two means by examining...
A Comparison of Alternate Statistical Modeling Strategies for Analyzing Length of Stay after CABG Surgery, Health Services & Outcomes Research Methodology (2002)
Investigators in clinical research are often interested in determining the association between patient characteristics and...
A Comparison of Bayesian Methods for Profiling Hospital Performance, Medical Decision Making (2002)
There is a growing interest in the use of Bayesian methods for profiling institutional performance....
A Comparison of Methods for Analyzing Health Related Quality of Life Measures, Value in Health (2002)
Objectives: Self-reported health status is often measured using psychometric or utility indices that provide a...
A Multicenter Study of the Coding Accuracy of Hospital Discharge Administrative Data for Cardiac Care Unit Patients in Ontario, American Heart Journal (2002)
Background: Cardiac health services researchers frequently use cohorts derived from administrative hospital discharge abstract data...
Adverse Effects of Observational Studies When Examining Adverse Effects of Drugs: Case-Control Studies with Low Prevalence of Exposure, Drug Safety (2002)
Objectives: The case-control study is commonly used to examine adverse drug events, in which prevalence...
Bayesian Extensions of the Tobit Model for Analyzing Measures of Health Status, Medical Decision Making (2002)
Self-reported health status is often measured using utility indices that provide a score intended to...
Bayeswatch: An Overview of Bayesian Statistics, Journal of Evaluation in Clinical Practice (2002)
Increasingly, clinical research is evaluated on the quality of its statistical analysis. Traditionally, statistical analyses...
Trends in drug prescriptions among elderly residents of Ontario in the weeks after September 11, 2001, Journal of the American Medical Association (2002)
A Comparison of a Bayesian versus a Frequentist Method for Profiling Hospital Performance, Journal of Evaluation in Clinical Practice (2001)
The objective of this study was to compare the classification of hospitals as outcomes outliers...
An Introduction to Multilevel Regression Models, Canadian Journal of Public Health (2001)
Data in health research are frequently structured hierarchically. For example, data may consist of patients...
The Use of the Tobit Model for Analyzing Measures of Health Status, Quality of Life Research (2000)
Self-reported health status is often measured using psychometric or utility indices that provide a score...