Seminars


For further information on any CSM events please e-mail: csm@lshtm.ac.uk.


Centre for Statistical Methodology Seminar
Friday 26 May 2017, 12:45-2:00pm
LG9, Keppel Street
Information anchored sensitivity analysis for randomised controlled trials via Multiple Imputation
Suzie Cro (Imperial College London)

Abstract: Controlled Multiple Imputation procedures have been proposed for contextually relevant accessible sensitivity analysis of clinical trials with missing data. The so called `δ- method’ enables trialists to explore the impact of unobserved patients having a poorer/better response than those observed. Reference based imputation procedures allow us to explore the impact of unobserved patients behaving like a specified reference group, typically control/placebo. Such sensitivity analysis should not inject information ‘by the back door.’ Neither do we want to lose value information collected in the trial. In this presentation we argue that sensitivity analysis of the type proposed should preserve the information loss due to missing data in the primary analysis. We refer to this as the information anchoring principle. We present theoretical and simulation results which show how an information anchored variance estimate is obtained for the treatment estimator when using the discussed methods. This provides a solid justification for their practical use, which we illustrate with the analysis of a chronic asthma trial.

26th Bradford Hill Memorial Lecture
Monday 12 June 2017, 5:00pm
John Snow Lecture Theatre, Keppel Street
Improving health by improving trials: from outcomes to recruitment and back again
Prof Paula Williamson (University of Liverpool)
Register here: www.lshtm.ac.uk/bhill2017

Centre for Statistical Methodology Seminar
Multivariate Methods Theme
Tuesday 20 June 2017, 12:45-2:00pm
LG6, Keppel Street
Correspondence analysis for studying food perception in Europe
Prof Eric Beh (University of Newcastle, Australia)

Abstract: Correspondence analysis is a statistical technique that provides a visual perspective to the association structure between categorical variables. In this talk we shall highlight the practical aspects of correspondence analysis and some of the recent developments made in this area of research. We shall focus on the data of Guerrero et al. (2010, Food Quality & Preference), and studied by Beh et al. (2011, Food Quality & Preference), which investigates how the word “Traditional” was perceived across six regions in Europe; Flanders (Belgium), Burgundy (France), Lazio (Italy), Akershus (Norway), Warsaw (Poland) and Catalonia (Spain).

Centre for Statistical Methodology Seminar
Analysis of Clinical Trials Theme
Friday 30 June 2017, 12:45-2:00pm
LG9, Keppel Street
Design and analysis of randomised trials with treatment-related clustering
Rebecca Walwyn (University of Leeds)

Abstract: Nesting of patients within therapists in psychotherapy trials creates an additional level within the design. The multilevel nature of this design has implications for the precision, internal and external validity of estimates of the treatment effect. Prior to or during a trial, psychotherapies are allocated to therapists and therapists are assigned to patients such that the therapist becomes part of the causal pathway from the intervention to the patient. It is therefore important to consider not only the relationship between interventions and patients but also relationships between interventions and therapists and between therapists and patients. Research designs comparing the effects of therapeutic approaches, therapist characteristics and packages of the two can be unified by viewing therapists as an important source of variability within psychotherapy outcome studies. Methodological considerations arising from therapist variation will be discussed, drawing together and building upon the associated psychotherapy and statistical literatures. Parallels will also be made with related designs and methods of analysis.

Centre for Statistical Methodology Seminar
Friday 1 December 2017, 12:45-2:00pm
LG9, Keppel Street
Title TBC
Prof Patricia Solomon (University of Adelaide)