Markov chain montecarlo method applied to rounding zeros of compositional data: first approach

As stated in Aitchison (1986), a proper study of relative variation in a compositional data set should be based on logratios, and dealing with logratios excludes dealing with zeros. Nevertheless, it is clear that zero observations might be present in real data sets, either because the corresponding part is completely absent –essential zeros– or because it is below detection limit –rounded zeros. Because the second kind of zeros is usually understood as “a trace too small to measure”, it seems reasonable to replace them by a suitable small value, and this has been the traditional approach. As stated, e.g. by Tauber (1999) and by Martín-Fernández, Barceló-Vidal, and Pawlowsky-Glahn (2000), the principal problem in compositional data analysis is related to rounded zeros. One should be careful to use a replacement strategy that does not seriously distort the general structure of the data. In particular, the covariance structure of the involved parts –and thus the metric properties– should be preserved, as otherwise further analysis on subpopulations could be misleading. Following this point of view, a non-parametric imputation method is introduced in Martín-Fernández, Barceló-Vidal, and Pawlowsky-Glahn (2000). This method is analyzed in depth by Martín-Fernández, Barceló-Vidal, and Pawlowsky-Glahn (2003) where it is shown that the theoretical drawbacks of the additive zero replacement method proposed in Aitchison (1986) can be overcome using a new multiplicative approach on the non-zero parts of a composition. The new approach has reasonable properties from a compositional point of view. In particular, it is “natural” in the sense that it recovers the “true” composition if replacement values are identical to the missing values, and it is coherent with the basic operations on the simplex. This coherence implies that the covariance structure of subcompositions with no zeros is preserved. As a generalization of the multiplicative replacement, in the same paper a substitution method for missing values on compositional data sets is introduced

Knowledge integration within an applied mobile robot summer course

This paper presents the use of a mobile robot platform as an innovative educational tool in order to promote and integrate different curriculum knowledge. Hence, it is presented the acquired experience within a summer course named ldquoapplied mobile roboticsrdquo. The main aim of the course is to integrate different subjects as electronics, programming, architecture, perception systems, communications, control and trajectory planning by using the educational open mobile robot platform PRIM. The summer course is addressed to a wide range of student profiles. However, it is of special interests to the students of electrical and computer engineering around their final academic year. The summer course consists of the theoretical and laboratory sessions, related to the following topics: design & programming of electronic devices, modelling and control systems, trajectory planning and control, and computer vision systems. Therefore, the clues for achieving a renewed path of progress in robotics are the integration of several knowledgeable fields, such as computing, communications, and control sciences, in order to perform a higher level reasoning and use decision tools with strong theoretical base

Numbers game

This is an exercise to use with groups. It was sent to Debra Morris in 2007, by David Jaques, an educationalist with many years' experience in groupwork.

Conways Game of Life JavaScript Exercise

For students learning JavaScript programming, this exercise sets out a fairly complete template for a DHTML implementation of Life. Students have to program the missing sections of code and attempt the extra features described. Only I have the password to unlock the solution!

Intro to Applied Maths

Exercises and solutions for a second year applied maths course.

Agile Game: A Project Management Game for Agile Methods

Since mid-1990s, companies have adopted agile methods and incorporated them in their development methodologies. For this reason, future project managers and developers need to have a full understanding of these methods. At present, the university’s approach to agile methods is theoretical and is not reflected during the development of a product and their practical use. The purpose of this project is the creation of a software system in the form of a game, named Agile Game, which simulates their use. The system is designed for use as supplementary material in lectures, to help students understand agile methods, to present their use within a project, and to demonstrate how they differ from traditional project management methodologies. The final system, which is web based, was implemented using PHP, MySQL and JavaScript. It was fully tested against the requirements and evaluated by peer students. The evaluation showed that the majority of users were satisfied with the system but they thought that it should contain more detailed information at every step of the game. For this reason, some parts of the design and the content were reviewed to meet user requirements.

Applied Biomechanics for Foundations of Safe Practice

This resource is for Health Scientist

Game Theory and Addiction

A brief one lecture introduction to Game Theory and Addiction techniques for building a games.

Game Theory

The 2013 Version of the Game Theory Presentation, now with an extra game.

Introduction to Game Design and Development

This is the introductory lecture to COMP3218. We introduce ourselves, cover the philosophy of the course, the structure and assessment process, and lead an initial game design exercise.