1 |
Predictive modelling of assisted conception data with embryo-level covariates : statistical issues and applicationStylianou, Christos January 2011 (has links)
Statistical modelling of data from the embryo transfer process of In-Vitro Fertilization (IVF) treatments is motivated by the need to perform statistical inference for potential factors and to develop predictive models for these treatments. The biggest issue arising when modelling these treatments is that a number of embryos are transferred but unless all of the embryos get implanted or fail to implant then it is not possible to identify which of the embryos implanted. Little work has been done to address this partial observability of the outcome as it arises in this context. We adopt an Embryo-Uterus (EU) framework where a patient response has distinct uterine and embryo components. This framework is used to construct statistical models, expand them to allow for clustering effects and develop a package that will enable the fitting and prediction of these models in STATA. The capabilities of this package are demonstrated in two real datasets, aimed in investigating the effect of a new embryo prognostic variable and the effect of patient clustering in these treatments. In a simulation study EU models are shown to be capable of identifying a patient covariate either as a predictor of uterine receptivity or embryo viability. However a simulation case study shows that a considerable amount of information about the embryo covariate is lost due to the partial observability of the outcome. Further simulation work evaluating the performance of a number of proposed alternatives to the EU model shows that these alternatives are either biased or conservative. The partially observed cycles are finally considered as a missing data problem and two novel modelling approaches are developed which are able to handle the structure of these treatments. These novel models, based on multiple imputation and probability weighting, are compared to the EU model using simulation in terms of predictive accuracy and are found to have similar predictive accuracy to the EU model.
|
2 |
Women's experiences of vaginismus and its treatment : an interpretative phenomenological analysisJohnston, Sarah Louise January 2013 (has links)
Female sexual pain is a common problem affecting women worldwide yet remains a poorly researched area of women’s sexual health. Dyspareunia and vaginismus are two types of sexual pain disorder each having psychological and physical health consequences for women and their partners. Part 1: A literature review of the qualitative research literature exploring women’s experiences of sexual pain disorders and their treatment was conducted adopting a narrative synthesis approach. Searches of psychological and medical electronic databases highlighted the paucity of research exploring women’s experiences of sexual pain disorders. Ten studies met the inclusion criteria for the review. The type of qualitative method and quality varied. Findings highlighted the complexity of women’s experiences of sexual pain. Positive experiences of treatment identified alternative benefits of treatment in addition to the traditional outcome of vaginal penetration and penetration without pain. Existing literature has focussed on dyspareunia, and further research is needed on vaginismus. Part 2: The research study used an Interpretative Phenomenological Analysis (IPA) of women’s experiences of vaginismus. Three women were interviewed about their experiences of vaginismus and the treatment they received. Interview transcripts were analysed using IPA. The findings identified the complexity of experiencing vaginismus, the struggle the women faced when trying to make sense of their vaginismus and the wider impact of these experiences on their identity. The findings highlight the value of psychological therapy with this client group and of the need to raise awareness amongst primary care professionals whom women with vaginismus are likely to consult in the first instance. Part 3: A critical appraisal of the research process is presented with focus on the experience of conducting qualitative research as a trainee clinical psychologist. A discussion of the findings is presented in the context of critical reflections on both the strengths and limitations of the study.
|
Page generated in 0.0183 seconds