This comprehensive institute is designed to develop skills that are useful in qualitative and mixed methods research, including:
Structuring and conducting an interview
Selecting an appropriate sample
Organizing and facilitating a focus group
Managing, coding and analyzing data
Publishing your work
Use and application of NVivo software. Advanced NVivo training will also be available.
General Registration (3 days): $850 Student rate (3 days): $450 Group rate (3 days, 3 people or more - contact email@example.com to register): $450 Lectures-only (2 days): $550
Abstract: In many circumstances, medical studies evaluating the efficacy of an intervention need either long follow-up periods or expensive or invasive procedures to obtain the primary outcome. This motivates the considerable attention to surrogate evaluation in recent years, which aims to use alternative measures ("surrogate marker(s)") in lieu of the primary outcome to evaluate the efficacy of an intervention. However, conventional surrogate evaluation methods fail to provide a causal interpretation, as surrogate markers that are conditional on in regression, are post-randomization variables. Principal surrogacy, defined based on the concept of principal stratification, overcomes such shortcomings. The current literature of principal surrogacy focuses on normally distributed continuous primary outcomes or binary outcomes. We propose a shared gamma frailty proportional hazard causal model to study principal surrogacy for time-to-event primary outcomes. The proposed model is constructed under the potential outcome framework with principal stratification approach, and a gamma frailty model is used to correlates the potential outcomes of an individual under different treatment arms. With the proposed model, we define the principal hazard ratio, expected associative effect and expected dissociative effect to evaluate principal surrogacy. Because of the complicated missing data structure, we adopt a Bayesian estimation method using Markov chain Monte Carlo algorithm. We use simulations to study the repeated sampling property of the proposed model. We illustrate the proposed model and estimation method with a randomized clinical trial of colorectal cancer.