University of Plymouth

About: University of Plymouth is a education organization based out in Plymouth, Plymouth, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 7301 authors who have published 20396 publications receiving 679758 citations.

Improved curve fits to summary survival data: application to economic evaluation of health technologies.

Abstract: Mean costs and quality-adjusted-life-years are central to the cost-effectiveness of health technologies. They are often calculated from time to event curves such as for overall survival and progression-free survival. Ideally, estimates should be obtained from fitting an appropriate parametric model to individual patient data. However, such data are usually not available to independent researchers. Instead, it is common to fit curves to summary Kaplan-Meier graphs, either by regression or by least squares. Here, a more accurate method of fitting survival curves to summary survival data is described. First, the underlying individual patient data are estimated from the numbers of patients at risk (or other published information) and from the Kaplan-Meier graph. The survival curve can then be fit by maximum likelihood estimation or other suitable approach applied to the estimated individual patient data. The accuracy of the proposed method was compared against that of the regression and least squares methods and the use of the actual individual patient data by simulating the survival of patients in many thousands of trials. The cost-effectiveness of sunitinib versus interferon-alpha for metastatic renal cell carcinoma, as recently calculated for NICE in the UK, is reassessed under several methods, including the proposed method. Simulation shows that the proposed method gives more accurate curve fits than the traditional methods under realistic scenarios. Furthermore, the proposed method achieves similar bias and mean square error when estimating the mean survival time to that achieved by analysis of the complete underlying individual patient data. The proposed method also naturally yields estimates of the uncertainty in curve fits, which are not available using the traditional methods. The cost-effectiveness of sunitinib versus interferon-alpha is substantially altered when the proposed method is used. The method is recommended for cost-effectiveness analysis when only summary survival data are available. An easy-to-use Excel spreadsheet to implement the method is provided.

A high-resolution late Holocene lake isotope record from Turkey and links to North Atlantic and monsoon climate

Abstract: A high resolution proxy record of precipitation and evaporation variability through the past 1700 yr from δ18O analysis of a varved lake sequence from central Turkey shows rapid shifts between dry periods (AD 300–500 and AD 1400–1950) and wetter intervals (AD 560–750 and AD 1000–1350). Changes are consistent with changes in instrumental and proxy records of the Indian monsoon, dry summers in the Eastern Mediterranean being associated with periods of enhanced monsoon rainfall. In addition major shifts in the record are coherent with changes in North Atlantic winter climate with cold, wet periods in the Alps occurring at times of dry Turkish climate.

Cognitive style and instructional preferences

Abstract: The aim of the study was to investigate the relationship between learners' cognitive styles and their instructional preferences. The sample consisted of 240 business studies students at a UK university. Subjects' cognitive styles were assessed using theCognitive Styles Analysis (which assesses the wholist-analytical and verbaliser-imager dimensions of style) and their instructional preferences assessed using an instructional preferences inventory which consisted of three sub-inventories (instructional method, instructional media and assessment method). Overall subjects favoured dependent methods, print based media and informal assessment methods. There was a significant main effect of wholist-analytical style on collaborative method preference (role play, group discussions and business games) and non-print based media preference (overhead transparencies, slides and videos). There was an interaction of the two dimensions of style and gender in their effect on informal assessment method preferences (individual and group assignments and multiple choice and short answertype questions). The findings are discussed in terms of: (i) models of the cognitive style construct; (ii) the practical implications of individual differences in style and preference.