Brunel University London

About: Brunel University London is a education organization based out in London, United Kingdom. It is known for research contribution in the topics: Context (language use) & Large Hadron Collider. The organization has 10918 authors who have published 29515 publications receiving 893330 citations. The organization is also known as: Brunel & University of Brunel.

Inflation Uncertainty, Output Growth Uncertainty and Macroeconomic Performance

Abstract: We use a bivariate generalized autoregressive conditionally heteroskedastic (GARCH) model of inflation and output growth to examine the causality relationship among nominal uncertainty, real uncertainty and macroeconomic performance measured by the inflation and output growth rates. The application of the constant conditional correlation GARCH(1,1) model leads to a number of interesting conclusions. First, inflation does cause negative welfare effects, both directly and indirectly, i.e. via the inflation uncertainty channel. Secondly, in some countries, more inflation uncertainty provides an incentive to Central Banks to surprise the public by raising inflation unexpectedly. Thirdly, in contrast to the assumptions of some macroeconomic models, business cycle variability and the rate of economic growth are related. More variability in the business cycle leads to more output growth.

Commentary and Issues : Who knows best? Evidence-based practice and the service user contribution:

Abstract: This paper reviews the assumptions underlying traditional medical research and critiques the concept of ‘evidence-based practice’. In particular, it identifies and counters three basic tenets of this approach: the alleged need for objectivity in research, the notion of hierarchies of evidence and the primacy of systematic reviews. Instead, the paper argues for a new emphasis on ‘knowledge-based practice’, recognizing that the practice wisdom of health and social care practitioners and the lived experience of service users can be just as valid a way of knowing the world as formal research.

A Comprehensive Investigation of the Role of Imbalanced Learning for Software Defect Prediction

Abstract: Context: Software defect prediction (SDP) is an important challenge in the field of software engineering, hence much research work has been conducted, most notably through the use of machine learning algorithms. However, class-imbalance typified by few defective components and many non-defective ones is a common occurrence causing difficulties for these methods. Imbalanced learning aims to deal with this problem and has recently been deployed by some researchers, unfortunately with inconsistent results. Objective: We conduct a comprehensive experiment to explore (a) the basic characteristics of this problem; (b) the effect of imbalanced learning and its interactions with (i) data imbalance, (ii) type of classifier, (iii) input metrics and (iv) imbalanced learning method. Method: We systematically evaluate 27 data sets, 7 classifiers, 7 types of input metrics and 17 imbalanced learning methods (including doing nothing) using an experimental design that enables exploration of interactions between these factors and individual imbalanced learning algorithms. This yields 27 × 7 × 7 × 17 = 22491 results. The Matthews correlation coefficient (MCC) is used as an unbiased performance measure (unlike the more widely used F1 and AUC measures). Results: (a) we found a large majority (87 percent) of 106 public domain data sets exhibit moderate or low level of imbalance (imbalance ratio $ 10; median = 3.94); (b) anything other than low levels of imbalance clearly harm the performance of traditional learning for SDP; (c) imbalanced learning is more effective on the data sets with moderate or higher imbalance, however negative results are always possible; (d) type of classifier has most impact on the improvement in classification performance followed by the imbalanced learning method itself. Type of input metrics is not influential. (e) only ${\sim} 52\%$ ∼ 52 % of the combinations of Imbalanced Learner and Classifier have a significant positive effect. Conclusion: This paper offers two practical guidelines. First, imbalanced learning should only be considered for moderate or highly imbalanced SDP data sets. Second, the appropriate combination of imbalanced method and classifier needs to be carefully chosen to ameliorate the imbalanced learning problem for SDP. In contrast, the indiscriminate application of imbalanced learning can be harmful.

Superpixel-Based Fast Fuzzy C-Means Clustering for Color Image Segmentation

Abstract: A great number of improved fuzzy c-means (FCM) clustering algorithms have been widely used for grayscale and color image segmentation. However, most of them are time-consuming and unable to provide desired segmentation results for color images due to two reasons. The first one is that the incorporation of local spatial information often causes a high computational complexity due to the repeated distance computation between clustering centers and pixels within a local neighboring window. The other one is that a regular neighboring window usually breaks up the real local spatial structure of images and thus leads to a poor segmentation. In this work, we propose a superpixel-based fast FCM clustering algorithm that is significantly faster and more robust than state-of-the-art clustering algorithms for color image segmentation. To obtain better local spatial neighborhoods, we first define a multiscale morphological gradient reconstruction operation to obtain a superpixel image with accurate contour. In contrast to traditional neighboring window of fixed size and shape, the superpixel image provides better adaptive and irregular local spatial neighborhoods that are helpful for improving color image segmentation. Second, based on the obtained superpixel image, the original color image is simplified efficiently and its histogram is computed easily by counting the number of pixels in each region of the superpixel image. Finally, we implement FCM with histogram parameter on the superpixel image to obtain the final segmentation result. Experiments performed on synthetic images and real images demonstrate that the proposed algorithm provides better segmentation results and takes less time than state-of-the-art clustering algorithms for color image segmentation.