The Work of Foster and Partners Specialist Modelling Group

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Crafting networks to achieve, or not achieve, chaotic states

The influence of networks topology on collective properties of dynamical systems defined upon it is studied in the thermodynamic limit. A network model construction scheme is proposed where the number of links, the average eccentricity and the clustering coefficient are controlled. This is done by rewiring links of a regular one dimensional chain according to a probability $p$ within a specific range $r$, that can depend on the number of vertices $N$. We compute the thermodynamic behavior of a system defined on the network, the $XY-$rotors model, and monitor how it is affected by the topological changes. We identify the network dimension $d$ as a crucial parameter: topologies with d\textless{}2 exhibit no phase transitions while ones with d\textgreater{}2 display a second order phase transition. Topologies with $d=2$ exhibit states characterized by infinite susceptibility and macroscopic chaotic/turbulent dynamical behavior. These features are also captured by $d$ in the finite size context

Causal inference taking into account unobserved confounding

Causal inference with observational data can be performed under an assumption of no unobserved confounders (unconfoundedness assumption). There is, however, seldom clear subject-matter or empirical evidence for such an assumption. We therefore develop uncertainty intervals for average causal effects based on outcome regression estimators and doubly robust estimators, which provide inference taking into account both sampling variability and uncertainty due to unobserved confounders. In contrast with sampling variation, uncertainty due unobserved confounding does not decrease with increasing sample size. The intervals introduced are obtained by deriving the bias of the estimators due to unobserved confounders. We are thus also able to contrast the size of the bias due to violation of the unconfoundedness assumption, with bias due to misspecification of the models used to explain potential outcomes. This is illustrated through numerical experiments where bias due to moderate unobserved confounding dominates misspecification bias for typical situations in terms of sample size and modeling assumptions. We also study the empirical coverage of the uncertainty intervals introduced and apply the results to a study of the effect of regular food intake on health. An R-package implementing the inference proposed is available.Comment: Biometrics 201

Between eternity and actualization: the co-evolution of the fields of communication in the Vatican

Most research on structuration or the appropriation of ICT in organizations has put aside the problem of dyschronies. It has not taken into account the differences in nature, speed, and temporality of changes that co-exist within an organization. To address this limitation, the author of this paper suggests a model based on the theory of practice and neo-institutionalist perspectives, so as to make sense of the co-evolution of intra-organizational fields. This model, which proposes a balance between various institutional tensions, has been worked out inductively from a longitudinal case study on communication fields within the Roman Curia, the administrative headquarters of the Catholic Church located in the Vatican. These tensions are related to socio-technical, socio-theological, socio-organizational, and socio-economic areas. A set of propositions regarding the link between intra-organizational fields and tensions and the relationships between intra-organizational fields (parallel, convergent, and competing evolutions) is proposed.Keywords: Dyschronies; structuration; intra-organizational fields; communication; medias; ICT; Roman Curia

American and European social embeddedness in IS research: the case of structurational approaches.

Whether in Europe or in North America, Structuration Theory has been widely applied in Information System research. Looking at some structurationists’ trajectories, it seems that European and American researchers correspond each to specific sub-theoretical streams. After having put forward institutional explanations of the overall dynamic, we suggest analysing the situation from an epistemological point of view: the various conceptions of management enacted by the different structurationist leaders. This results in the disappearance of the apparent continental dichotomy we first raised. As a conclusion, we propose two perspectives for the new European academy of management.Key-words: Structuration theory; social embeddedness of management research; research trajectories; epistemology

Strategic Alignment: What Else? A Practice Based View of IS Value.

Pour l’essentiel, les recherches traitant des valeurs stratégiques du SI restent dans le paradigme de l’alignement stratégique, et utilisent des notions telles que celles de "processus" ou "d’activités". En s’appuyant sur la perspective offerte par les théories de la pratique, cet article offre une alternative en distinguant trois formes de praxis et des valeurs spécifiques.Literature about IS strategic management or IS strategic value is abundant. Nonetheless, the bulk of existing studies are focused on the concept of alignment. They do not make sense of a strategic value "in practice" and still draw on notions such as activity or process to make sense of alignment. By means of a practice-based view of technology, three praxis are suggested here for the modeling of strategic value: legitimacy-related (based on adoption praxis), assimilative (related to design and acceptance praxis) and appropriative (linked to local adaptation and improvisation praxis). They are introduced by means of a "thought experiment" (a short story about a rifle).Strategic alignment; IS strategic value; Practice-based views; strategic value in practice; thought experiments;