Issues in the analysis of co-authorship networks

Scientific collaboration is a complex phenomenon that improves the sharing of competences and the production of new scientific knowledge. Social Network Analysis is often used to describe the scientific collaboration patterns defined by co-authorship relationships. Different phases of the analysis of collaboration are related to: data collection, network boundary setting, relational data matrix definition, data analysis and interpretation of results. The aim of this paper is to point out some issues that arise in these different phases, highlighting: (i) the use of local archives versus international bibliographic databases; (ii) the use of different approaches for setting boundaries in a whole-network; (iii) the definition of a co-authorship data matrix (binary and weighted ties) and (iv) the analysis and the interpretation of network measures for co-authorship data. We discuss the different choices that can be made in these phases within an illustrative example on real data which is referred to scientific collaboration among researchers affiliated to an academic institution. In particular, we compare global and actor-level network measures computed from binary and weighted co-authorship networks in different disciplines.     

Co-monotonicity of optimal investments and the design of structured financial products

We prove that, under very weak conditions, optimal financial products on complete markets are co-monotone with the reversed state price density. Optimality is meant in the sense of the maximization of an arbitrary preference model, e.g., expected utility theory or prospect theory. The proof is based on a result from transport theory. We apply the general result to specific situations, in particular the case of a market described by the Capital Asset Pricing Model or the Black–Scholes model, where we derive a generalization of the two-fund-separation theorem and give an extension to APT factor models and structured products with several underlyings. We use our results to derive a new approach to optimization in wealth management, based on a direct optimization of the return distribution of the portfolio. In particular, we show that optimal products can (essentially) be written as monotonic functions of the market return. We provide existence and nonexistence results for optimal products in this framework. Finally we apply our results to the study of bonus certificates, show that they are not optimal, and construct a cheaper product yielding the same return distribution.     

Enticing the Stork: Can we Evaluate Pro‐Natal Policies Before Having Children?

Aside from immigration, the only meaningful demographic lever available to policymakers attempting to moderate the rate of ageing is the birth rate. This article departs from previous analyses of pro‐natal policies by studying determinants of pro‐natal options ex ante, which represents an advantage for policymakers looking to craft policies with prior knowledge of whether or not a demographic policy will have a significant effect. Our multinomial regression model for a US sample involving college students shows that the preferred choice of pro‐natal incentive is dependent on gender, economic class, number of planned children and migrant status. We find that females are more likely than males to choose any pro‐natal incentive over no incentive. The highest odds for increasing planned number of children are for maternity leave and parental leave options. Respondents associating themselves with the poorest economic class are more likely to choose daycare or government grant as pro‐natal options.     

Looking into the abyss? Brazil at the mid-2010s

In 2015, the Brazilian economy was afflicted by a lethal combination of a falling level of activity and accelerating inflation. Expectations for 2016 are equally or even more adverse, since the effects of rising unemployment emerge only after a lag. The domestic debate has opposed analysts who believe the crisis is due exclusively to past policy mistakes to analysts who believe that all was well until the government decided to implement austerity policies in 2015. A closer examination of the evidence shows that in fact both reasons contributed to causing the crisis, but it also suggests that its depth has a more proximate cause in the political collapse of the federal government in 2015, which led Brazilian society to an impasse for which a solution is not yet in view.     

Ethical Codes in Sports Organizations: Classification Framework,Content Analysis,and the Influence of Content on Code Effectiveness

Although there is a growing body of research on social media, only few studies have considered organic products. Therefore, this study mapped the diffusion path of the social media resources for organic products in Mexico and South Korea through Twitter and compared the contents of tweets about organic products in terms of their semantic and hyperlink networks using webometric methods. The results indicate that for organic products, Koreans sent tweets much more frequently than Mexicans. Mexican tweets focused on basic food products in street markets, whereas Korean tweets highlighted promotions and firms, revealing the corporatist structure of its economy. In both cases, the findings support Twitter as a useful tool for Word-of-Mouth Communication on the online environment, among product consumers, and between consumers and enterprises.     

ON VALUING STOCHASTIC PERPETUITIES USING NEW LONG HORIZON STOCK PRICE MODELS DISTINGUISHING BOOMS,BUSTS, AND BALANCED MARKETS

For longer horizons, assuming no dividend distributions, models for discounted stock prices in balanced markets are formulated as conditional expectations of nontrivial terminal random variables defined at infinity. Observing that extant models fail to have this property, new models are proposed. The new concept of a balanced market proposed here permits a distinction between such markets and unduly optimistic or pessimistic ones. A tractable example is developed and termed the discounted variance gamma model. Calibrations to market data provide empirical support. Additionally, procedures are presented for the valuation of path dependent stochastic perpetuities. Evidence is provided for long dated equity linked claims paying coupon for time spent by equity above a lower barrier, being underpriced by extant models relative to the new discounted ones. Given the popularity of such claims, the resulting mispricing could possibly take some corrections. Furthermore for these new discounted models, implied volatility curves do not flatten out at the larger maturities.     

Orientation to sustainability and strategic positioning of destinations: an analysis of international tourism websites

The communication that Destination Management Organizations (DMOs) address to destination stakeholders plays a central role in attracting attention and resources for sustainable destination development and disclosing the efforts made to be a sustainable territory. There has been extensive analysis on the role of official tourism websites that addresses both DMO's internal and external stakeholders. However, less exploration is available on the relationship between the contents disclosed through tourism websites and the strategic positioning of the destination. This study empirically examines that link with a focus on ‘green/sustainable/responsible' travel. Results show a positive association between the orientation to sustainability in online communication and both sustainable regulation of the tourism sector and tourism development. In contrast, there is no significant association with destination size, tourism maturity and pricing policies.     

The political economy of pricing and capacity decisions for congestible local public goods in a federal state

This paper studies the political economy of pricing and investment for excludable and congestible public goods in a federal state. Although the model applies to many local congestible public facilities (such as libraries, museums and public swimming facilities), our main motivation is the problem of providing and pricing road infrastructure in federal states. The two-region model we develop allows for spill-overs between regions, it takes into account congestion, and it captures demand heterogeneity both between and within regions. Regional decisions are taken by majority voting; federal decisions are taken by a minimum winning coalition in a legislature of regionally elected representatives. We have the following results. First, when users form the majority in at least one region, decentralized decision making performs certainly better than centralized decision making if spill-overs are not too large. Centralized decisions may yield higher welfare than decentralization only if users have a large majority and the infrastructure in a given region is intensively used by both local and outside users. Second, if non-users form a majority in both regions, centralized decision making and decentralized decision making yield the same socially undesirable outcome, with prices that are much too high. Third, the performance of decentralized supply is strongly enhanced by local self-financing rules; this prevents potential exploitation of users within regions.     

Are sponsorship announcements good news for the shareholders? Evidence from international stock exchanges

The objective of this study is to analyse investors’ perceptions of sponsorship’s ability to increase brand equity, through the impact of sponsorship announcement on stock market value. An event study method, based on a unique sample of 293 worldwide sponsorship announcements from 2010, shows substantial negative abnormal returns following announcement dates. In addition, a cross-sectional regression analysis reveals the influence of several featured factors. Philanthropic sponsorships and sponsorships of events with distinctive values are less negatively perceived by investors, but US companies exhibit more negative returns in shareholder value than other firms. This study offers no support for varying impacts of event audience, renewal agreement, property sponsorship and title sponsorship on abnormal returns though.     

Limits to creative destruction and technologies in practice: the case of ham radio

Drawing on the structurationist notion of ‘technologies-in-practice’, this article analyses the different types of technological actions that users perform, after technological change, in order to keep a declining technology alive over time. The research question of the article is: How do technologies-in-practice based on the application of new technology hamper the creative destruction of old technology? The case study of ham radio technology and amateur radio operators is explored. The results of the investigation support the development of a technology-in-practice ‘experimentation’ and four inductive research propositions.