strbee analyzes a two-group clinical trial with a survival outcome, in which some subjects may "crossover" to receive the treatment of the other arm. Adjustment for treatment crossover is done by a randomization-respecting method that preserves the intention-to-treat p-value. Copyright 2002 by...

In the presence of dependent competing risks in survival analysis, the Cox proportional hazard model can be utilised to examine the covariate effects on the cause-specific hazard function for each type of failure. The use of the Cox model was proposed by Lunn and McNeil (Biometrics, 1995). Their...

Treatment changes in randomized trials are common: for example, in a trial evaluating psychotherapy, individuals allocated to psychotherapy may attend only partially or not at all; or in a trial evaluating a drug treatment, individuals allocated to no drug treatment may nevertheless receive the...

Multiple imputation is increasingly regarded as the standard method to account for partially observed data, but most methods have been based on cross-sectional imputation algorithms. Recently, a new multiple-imputation method, the two fold fully conditional specification (FCS) method, was...

Any analysis with incomplete data makes untestable assumptions about the missing data, and analysts are therefore urged to conduct sensitivity analyses. Ideally, a model is constructed containing a nonidentifiable parameter d, where d = 0 corresponds to the assumption made in the standard...

In epidemiology, measurement error or within-individual variation in exposures and confounders leads to attenuated effect estimates and inadequate control of confounding. Adjustment for measurement error is possible if its magnitude may be estimated from supplementary information, typically...

A new command metamiss performs meta-analysis when some or all studies have missing data. A variety of assumptions are available, including missing-at-random, missing=failure, worst and best cases, and incorporating a user-specified prior distribution for the degree of informative missingness....

Simulation studies are a powerful tool, but their analysis is not always done well; in particular, Monte Carlo standard errors are often not reported. I present a Stata program, - simsum-, which can output a range of summaries, including bias, precision of one method relative to another,...

In teaching logistic regression for case–control studies, I ask master’s students in epidemiology to assess an interaction between a 2-level exposure and a 4-level exposure using a likelihood-ratio test. Theory suggests that the test statistic has 3 degrees of freedom, but Stata uses 2...

Network meta-analysis involves synthesising the scientific literature comparing several treatments. Typically, two-arm and three-arm randomized trials are synthesized, and the aim is to compare treatments that have not been directly compared and often to rank the treatments. A difficulty is that...