Browsing by Author "Campbell, Michael J"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Sample size calculations for the design of cluster randomized trials: A summary of methodology.
    (Contemporary clinical trials, 2015-05) Gao, Fei; Earnest, Arul; Matchar, David B; Campbell, Michael J; Machin, David
    Cluster randomized trial designs are growing in popularity in, for example, cardiovascular medicine research and other clinical areas and parallel statistical developments concerned with the design and analysis of these trials have been stimulated. Nevertheless, reviews suggest that design issues associated with cluster randomized trials are often poorly appreciated and there remain inadequacies in, for example, describing how the trial size is determined and the associated results are presented. In this paper, our aim is to provide pragmatic guidance for researchers on the methods of calculating sample sizes. We focus attention on designs with the primary purpose of comparing two interventions with respect to continuous, binary, ordered categorical, incidence rate and time-to-event outcome variables. Issues of aggregate and non-aggregate cluster trials, adjustment for variation in cluster size and the effect size are detailed. The problem of establishing the anticipated magnitude of between- and within-cluster variation to enable planning values of the intra-cluster correlation coefficient and the coefficient of variation are also described. Illustrative examples of calculations of trial sizes for each endpoint type are included.
  • Thumbnail Image
    ItemOpen Access
    Society for Cardiovascular Magnetic Resonance 2020 Case of the Week series.
    (Journal of cardiovascular magnetic resonance : official journal of the Society for Cardiovascular Magnetic Resonance, 2021-10) Johnson, Jason N; Mandell, Jason G; Christopher, Adam; Olivieri, Laura J; Loke, Yue-Hin; Campbell, Michael J; Darty, Steve; Kim, Han W; Clark, Daniel E; Frischhertz, Benjamin P; Fish, Frank A; Bailey, Alison L; Mikolaj, Michael B; Hughes, Sean G; Oneugbu, Afiachukwu; Chung, Jina; Burdowski, Joseph; Marfatia, Ravi; Bi, Xiaoming; Craft, Jason; Umairi, Rashid A; Kindi, Faiza A; Williams, Jason L; Campbell, Michael J; Kharabish, Ahmed; Gutierrez, Manuel; Arzanauskaite, Monika; Ntouskou, Marousa; Ashwath, Mahi L; Robinson, Tommy; Chiang, Jeanie B; Lee, Jonan CY; Lee, MSH; Chen, Sylvia SM
    The Society for Cardiovascular Magnetic Resonance (SCMR) is an international society focused on the research, education, and clinical application of cardiovascular magnetic resonance (CMR). Case of the week is a case series hosted on the SCMR website ( https://www.scmr.org ) that demonstrates the utility and importance of CMR in the clinical diagnosis and management of cardiovascular disease. Each case consists of the clinical presentation and a discussion of the condition and the role of CMR in diagnosis and guiding clinical management. The cases are all instructive and helpful in the approach to patient management. We present a digital archive of the 2020 Case of the Week series of 11 cases as a means of further enhancing the education of those interested in CMR and as a means of more readily identifying these cases using a PubMed or similar search engine.