Quantitative Determination of the Relationship between Internal Validity and Bias in Software Engineering Experiments: Consequences for Systematic Literature Reviews

Quality assessment is one of the activities performed as part of systematic literature reviews. It is commonly accepted that a good quality experiment is bias free. Bias is considered to be related to internal validity (e.g., how adequately the experiment is planned, executed and analysed). Quality assessment is usually conducted using checklists and quality scales. It has not yet been proven;however, that quality is related to experimental bias. Aim: Identify whether there is a relationship between internal validity and bias in software engineering experiments. Method: We built a quality scale to determine the quality of the studies, which we applied to 28 experiments included in two systematic literature reviews. We proposed an objective indicator of experimental bias, which we applied to the same 28 experiments. Finally, we analysed the correlations between the quality scores and the proposed measure of bias. Results: We failed to find a relationship between the global quality score (resulting from the quality scale) and bias; however, we did identify interesting correlations between bias and some particular aspects of internal validity measured by the instrument. Conclusions: There is an empirically provable relationship between internal validity and bias. It is feasible to apply quality assessment in systematic literature reviews, subject to limits on the internal validity aspects for consideration.

Identification of Degraded Land in the Canary Islands; Tests and Reviews

Degraded Land is an area that either by natural causes (fires, floods, storms or volcanic eruptions) or more by direct or indirect causes of human action, has been altered or modified from its natural state. Restoration is an activity that initiates or accelerates the recovery of an ecosystem. It can be defined as the set of actions taken in order to reverse or reduce the damage caused in the territory. In the case of the Canary Islands there is a high possibility for the territory to suffer processes that degrade the environment, given that the islands are very fragile ecosystems. Added to this they are territories isolated from the continent, which complicates the process of restoring them. In this paper, the different types of common degraded areas in the Canary Islands are identified, as well as the proposed solutions for remediation, such as afforestation of agricultural land or landfill closure and restoration.

Mining mobile apps reviews to support release planning

The mobile apps market is a tremendous success, with millions of apps downloaded and used every day by users spread all around the world. For apps’ developers, having their apps published on one of the major app stores (e.g. Google Play market) is just the beginning of the apps lifecycle. Indeed, in order to successfully compete with the other apps in the market, an app has to be updated frequently by adding new attractive features and by fixing existing bugs. Clearly, any developer interested in increasing the success of her app should try to implement features desired by the app’s users and to fix bugs affecting the user experience of many of them. A precious source of information to decide how to collect users’ opinions and wishes is represented by the reviews left by users on the store from which they downloaded the app. However, to exploit such information the app’s developer should manually read each user review and verify if it contains useful information (e.g. suggestions for new features). This is something not doable if the app receives hundreds of reviews per day, as happens for the very popular apps on the market. In this work, our aim is to provide support to mobile apps developers by proposing a novel approach exploiting data mining, natural language processing, machine learning, and clustering techniques in order to classify the user reviews on the basis of the information they contain (e.g. useless, suggestion for new features, bugs reporting). Such an approach has been empirically evaluated and made available in a web-­‐based tool publicly available to all apps’ developers. The achieved results showed that the developed tool: (i) is able to correctly categorise user reviews on the basis of their content (e.g. isolating those reporting bugs) with 78% of accuracy, (ii) produces clusters of reviews (e.g. groups together reviews indicating exactly the same bug to be fixed) that are meaningful from a developer’s point-­‐of-­‐view, and (iii) is considered useful by a software company working in the mobile apps’ development market.

Análisis de la geometría de Pablo Palazuelo desde la visión del arquitecto

Esta investigación indaga sobre la relación entre el método geométrico empleado por Pablo Palazuelo y el proceso del proyecto arquitectónico. La elección de este pintor y escultor madrileño como hilo conductor de esta tesis no es fortuita, puesto que la arquitectura desempeña una influencia esencial sobre su obra. Un influjo que le llega en parte a través de su formación académica, dado que cursó estudios de arquitectura en la School of Arts and Crafts de la ciudad de Oxford (1933-1936). Así mismo diseñó propuestas estrechamente vinculadas a un lugar construido, con el consiguiente condicionante de las trazas del mismo. La hipótesis de trabajo formulada a partir de textos elaborados por autores como Víctor Nieto Alcaide y Juan Daniel Fullaondo sugería una interconexión con la arquitectura orgánica. Como comprobación del grado de profundidad en otros análisis publicados, se han seleccionado los textos que indagan en el proceso que el artista desarrollaba durante la producción de su obra, y se adentran en cuestiones estructurales que trascienden el ámbito formal. Siguiendo esta pauta, además de una acotación temporal, se han escogido los realizados por Santiago Amón, Carme Bonell, Valerio Bozal, Manuel J. Borja-Villel, Francisco Calvo Serraller, Claude Esteban, Julián Gállego, Teresa Grandas, Max Hölzer, George Limbour, Kevin Power y Carlos Rodríguez-Spiteri. A estos autores se suman las fuentes orales consultadas dentro de un entorno intrínsecamente próximo a sus realizaciones, procedentes de Pere Casanovas y Soledad Lorenzo. Además de personas que en diferentes etapas de su vida coincidieron por distintos motivos con sus realizaciones, como son Ramón Ayerza, Mariano Bayón, José Antonio Corrales, Luis Gordillo, Rafael Moneo, José Rodríguez-Spiteri y Antonio Tornero. A partir del acceso obtenido a los escritos, libros, bocetos y abundante obra gráfica y escultórica que atesora la Fundación del pintor, se ha podido elaborar un andamiaje tanto teórico como geométrico que ha servido de base para confrontar estas premisas. Esta empresa se ha estructurado en una narración que, además de los estudios precedentes citados, comienza con los cimientos del pensamiento de Palazuelo. Elaborada a partir de sus escritos, donde defendía un sincretismo que concilia las visiones de las culturas occidental y oriental. En los siguientes apartados, se han analizado las principales obras gráficas y escultóricas del autor haciendo un especial hincapié en el método productivo. Una gestación que se resiste a una mera enumeración cronológica, por lo que la clasificación que se propone en este trabajo trata de ser lo más fiel posible al espíritu expresado por Palazuelo basado en linajes y coherencias, para desvelar las herramientas empleadas y poder compararlas con el proceso del proyectual. Este recorrido se completa con una última sección se reúnen por primera vez las dieciséis obras y los dieciséis proyectos más representativos que ilustran la aproximación más directa que obró Palazuelo entre sus investigaciones geométricas y un locus determinado. Durante casi cuatro años se desarrolló un inventariado y catalogación pormenorizada de la documentación y piezas sobre papel, lienzo y metal realizadas por Palazuelo. Esta indagación saca a la luz un conjunto constituido por casi cuatro mil obras, en su mayoría inéditas, que constituyen el archivo de la citada institución. En definitiva, esta investigación construye un tejido gráfico y geométrico referido a uno de los artistas españoles más importantes del siglo XX, entreverado por su pensamiento teórico y realizaciones en dibujos, maquetas, esculturas y propuestas arquitectónicas. Las cuales permiten establecer los acuerdos y desacuerdos con el proceso de la arquitectura para proponer una nueva aproximación geométrica interdisciplinar. ABSTRACT This research investigates the relationship between the geometric method used by Palazuelo and the architectural design’s process. Choosing this Spanish painter and sculptor as thread of this thesis is not fortuitous, since the architecture has an essential influence on his work. An influx that arrives in part through his academic training, as he was an architecture student at the School of Arts and Crafts of the city of Oxford (1933-1936). Furthermore his proposals designed closely linked to a built place, therefore conditioned by its traces. The working hypothesis formulated from texts written by authors like Victor Nieto Alcaide and Juan Daniel Fullaondo suggested an interconnection with organic architecture. As a check on the degree of depth in other published reviews, articles that explore the process that the artist developed during the production of his work, and penetrate into structural issues beyond formal domain have been selected. Following this pattern, along with a temporal dimension, assays by Santiago Amón, Carme Bonell, Valerio Bozal, Manuel J. Borja-Villel, Francisco Calvo Serraller, Claude Esteban, Julián Gállego, Teresa Grandas, Max Hölzer, George Limbour, Kevin Power and Carlos Rodriguez-Spiteri have been selected. Oral sources within an inherently environment close to his achievements, as Pere Casanovas and Soledad Lorenzo, are also added. In addition to people coincided with his accomplishments, such as Ramón Ayerza, Mariano Bayón, José Antonio Corrales, Luis Gordillo, Rafael Moneo, José Rodríguez-Spiteri and Antonio Tornero. From obtained access to the writings, books, sketches and abundant graphic and sculptural work that holds the Foundation painter, it has been able to develop a theoretical and geometric framework that have served as the basis for confronting these premises. This dissertation has been structured in a narrative that ⎯in addition to the previously mentioned studies⎯, begins with the foundations of Palazuelo thought. A structure built from his writings, where he defended a syncretism that reconciles the views of Western and Eastern cultures. In the following sections, his main graphic and sculptural works have been analyzed with particular emphasis on the productive method. A process that resists mere chronological enumeration, so the classification proposed in this investigation tries to be as faithful as possible to the spirit expressed by Palazuelo, based on bloodlines and coherences, to uncover the tools he used and to compare them with the architectural design process. This tour is completed with a final chapter that gathers the sixteen proposals and sixteen works most representative projects that illustrate the more direct approach that Palazuelo worked between geometric investigations and a given locus. For nearly four years, a detailed inventory and cataloguing of documents and works on paper, canvas and metal made by Palazuelo was developed. This research brings to light a set consisting of nearly four thousand works, mostly unpublished, that constitute the current archive of the aforementioned institution. Ultimately, this research builds a graph and geometric fabric referred to one of the most important Spanish artists of the twentieth century, interspersed by his theoretical thinking and achievements in drawings, models, sculptures and architectural proposals. Which allow establishing agreements and disagreements with the process of architecture to propose a new geometric interdisciplinary approach.