On the minimum expected quantity for the validity of the chi-squared test in 2 2 2 tables

A 2 2 2 contingency table can often be analysed in an exact fashion by using Fisher's exact test and in an approximate fashion by using the chi-squared test with Yates' continuity correction, and it is traditionally held that the approximation is valid when the minimum expected quantity E is E S 5. Unfortunately, little research has been carried out into this belief, other than that it is necessary to establish a bound E>E*, that the condition E S 5 may not be the most appropriate (Martín Andrés et al., 1992) and that E* is not a constant, but usually increasing with the growth of the sample size (Martín Andrés & Herranz Tejedor, 1997). In this paper, the authors conduct a theoretical experimental study from which they ascertain that E* value (which is very variable and frequently quite a lot greater than 5) is strongly related to the magnitude of the skewness of the underlying hypergeometric distribution, and that bounding the skewness is equivalent to bounding E (which is the best control procedure). The study enables estimating the expression for the above-mentioned E* (which in turn depends on the number of tails in the test, the alpha error used, the total sample size, and the minimum marginal imbalance) to be estimated. Also the authors show that E* increases generally with the sample size and with the marginal imbalance, although it does reach a maximum. Some general and very conservative validity conditions are E S 35.53 (one-tailed test) and E S 7.45 (two-tailed test) for alpha nominal errors in 1% h f h 10%. The traditional condition E S 5 is only valid when the samples are small and one of the marginals is very balanced; alternatively, the condition E S 5.5 is valid for small samples or a very balanced marginal. Finally, it is proved that the chi-squared test is always valid in tables where both marginals are balanced, and that the maximum skewness permitted is related to the maximum value of the bound E*, to its value for tables with at least one balanced marginal and to the minimum value that those marginals must have (in non-balanced tables) for the chi-squared test to be valid.     

Choice Functions: Rationality re-Examined

On analyzing the problem that arises whenever the set of maximal elements is large, and a selection is then required (see Peris & Subiza 1998), we realize that logical ways of selecting among maximals violate the classical notion and axioms of rationality. We arrive at the same conclusion if we analyze solutions to the problem of choosing from a tournament (where maximal elements do not necessarily exist). So, in our opinion the notion of rationality must be discussed, not only in the traditional sense of external conditions (Sen 1993), but in terms of the internal information provided by the binary relation.     

Town Centre Management: Outlook from Portugal

In the last two decades, the Portuguese Government has responded to the decline of centres of commerce. In this paper, we analyse the three different experiences of town centre management (TCM) schemes developed in Portugal since the turn of the millennium. The first two stages were developed using public sector initiatives and their impacts were limited. The third stage is still under way and is composed of private projects created by local business owners. Taking Lisbon as a case study for this third stage we conclude that these projects have become a pro-active means of intervention in Portuguese town centres.     

Stream restoration in Andean cities: learning from contrasting restoration approaches

Urban Ecosystems - The Andes region is one of the fastest urbanizing regions of the world. The current rate of environmental degradation of streams in this region create an urgent need for...     

Rainfall interception capacity of tree species used in urban afforestation

Afforestation is inserted in the urban environment and interferes directly in the surface runoff. In order to quantify the rainfall interception by tree species, an experiment was carried out in the city of Uruaçu, Goiás, Brazil, with the four most common tree species in the urban afforestation of the region. The species chosen were the Mangifera indica (mango tree), the Caesalpinia peltophoroides (sibipiruna tree), the Pachira aquatica (munguba tree) and the Licania tomentosa (oiti). In order to register precipitation, ten pluviographs were used. They are capable of measuring precipitation over time in terms of duration, volume, and intensity. For events with a mean cumulative precipitation of 16.7 mm, the mean values of interception found in each species were: Mangifera indica - 8.0 mm; Pachira aquatica - 7.4 mm; Licania tomentosa - 7.2 mm; and Caesalpinia peltophoroides - 4.8 mm. The research confirms the importance of studies related to the identification of the species’ individual characteristics that interfere in the rainfall interception capacity and that can consequently contribute to urban drainage actions. In addition, it proves the existence of variations of rainfall interception in relation to rainfall events and during their occurrences and emphasizes the need for a careful definition of the species that will compose the urban afforestation.     

No reliable evidence for immediate noise-induced song flexibility in a suboscine

Urban Ecosystems - Vermilion flycatchers, a suboscine, sing songs with more elements in territories with higher urban noise levels. We tested the hypothesis that this pattern is achieved through...     

Interwoven migration narratives: identity and social representations in the Lusophone world

This article provides an exploratory analysis of the life narratives of migrants in the Portuguese-speaking world. By interweaving the life experiences of eight participants in three thematic clusters – ‘shared past’, language and sense of community – we propose a critique of the deep-seated idea of the Lusophone space as a community constructed by the harmonious conviviality of different countries and people. Drawing on contributions from cultural studies, social psychology, anthropology and sociology, we first aim to give voice to the human subjects who embark on migrations and then to understand how the engendered process of identity construction is framed by their social world, simultaneously reframing it. Thus, we aim at shedding light on the ways in which aspects of the political discourses on Lusophony are used (and are instrumental) to the migrants’ identity narrative (re)construction.     

Improving citizens’ online engagement via community managers: an explanatory study

The role of community manager is gaining importance as the proper usage of social media becomes a key factor for achieving more active involvement of citizens in social and political issues. Focused on Spanish local governments and in line with the literature of Excellence Theory, this paper aims to analyze whether some characteristics of the community manager function are determinant in their fostering of citizens’ online engagement via social media. In particular ‘independence’, ‘having access to the dominant coalition’, ‘gender diversity’, ‘continuous training’ and ‘culture of the organization’ are the characteristics considered in this paper. As to the main findings, this study confirms that community managers have not as yet achieved their goal of embedding the use of social media by citizens as a means of establishing more direct contact with their local governments. Moreover, in line with Excellence Theory, community managers of local governments should be aware of the importance of having direct access to key managers of the organization in order to better achieve the objectives of the organization and, more specifically, to increase citizens’ engagement. Furthermore, continuous training in issues related to social media truly helps develop the skills and potential of community managers. Likewise, an excellent communication department should rely on good professionals no matter their gender, and, in this sense, the gender of community managers is not a significant factor in their performance. However, the results of this study also reveal that in the case of public sector community managers, an authoritarian culture seems to be a determining factor for obtaining better results in enhancing citizens’ engagement.     

Analysis of social innovation on social networking services

ABSTRACT

Social network services are allowing more social connectivity and making possible sharing information and knowledge of a different nature. This article analyses if social workers related to active social policies from Malaga province (Spain) are using social network services to share information and knowledge and if there is a mirror between online and offline relationships. Since it is an experimental model, through virtual ethnography and through social network analysis methodology, we observed the presence, connectivity and analysed the structure of relationships that keep 235 professionals from 52 organizations in Facebook®. Moreover, the model uses the statistical technique of modularity for detecting online communities, which are compared with distribution of professionals in their organizations. Results show how social network services applied to social intervention are massively and frequently used by professionals. On the other hand, the detected communities reflect existence of analogy between online and offline relationships. The online structure shows a high degree of cohesion and how certain professionals have higher capacity of influence and diffusion depending on position in the online structure. It argues about the opportunity to incorporate social network services towards social intervention as a manner of social innovation to improve cooperation and diffusion of information and knowledge.     

A state of limbo: the politics of waiting in neo‐liberal Latvia

This article presents an ethnographic study of politics of waiting in a post‐Soviet context. While activation has been explored in sociological and anthropological literature as a neo‐liberal governmental technology and its application in post‐socialist context has also been compellingly documented, waiting as a political artefact has only recently been receiving increased scholarly attention. Drawing on ethnographic fieldwork at a state‐run unemployment office in Riga, this article shows how, alongside activation, state welfare policies also produce passivity and waiting. Engaging with the small but developing field of sociological literature on the politics of waiting, I argue that, rather than interpreting it as a clash between ‘neo‐liberal’ and ‘Soviet’ regimes, we should understand the double‐move of activation and imposition of waiting as a key mechanism of neo‐liberal biopolitics. This article thus extends the existing theorizations of the temporal politics of neo‐liberalism.