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The primary purpose of this study was to identify dimensions of weak tie relationships including characteristics (e.g., distinctive qualities, traits, or properties), functions (e.g., outcomes, purposes, or meanings derived from the interaction) and determinants of engagement to gain insight into the weak tie exchange process and develop frameworks that can be used to operationalize the concept. Data were collected through stories provided by participants during face-to-face interviews. Respondents recounted a situation when someone they did not know well and to whom they did not feel particularly close provided them with assistance. Over 70 stories were collected from 50 adults aged 65 and older who were active in their community. Stories collected were analyzed using an inductive approach that was supported by the concepts of interpersonal tie strength, loose connections, social exchange theory, and social support. Findings suggest that weak tie relationships occur in a variety of community settings and in response to a variety of daily challenges. The exchanges occur more frequently with acquaintances than strangers and the initiator of the exchange is generally the person offering support. The types of support offered are broad-based and include instrumental, emotional, and informational support. Weak tie exchanges range from one-time brief interactions to intermittent exchanges over extended periods, depending on the circumstances. Findings also suggest that weak ties have a specific task or purpose, encourage awareness about the value and purpose of social interactions, and influence participants' future social interactions. Six factors were identified as determinants of engagement in weak ties: situational factors, personal characteristics, judgments of responsibility, attitudes about helping behaviors, personal network type, and exchange history. The findings from this study provide a foundation for further conceptualization of weak ties and a framework on which to develop instruments to measure tie strength and the potential for engaging in weak tie exchanges. / Ph. D.

Previous research has suggested that individuals differ in their accuracy of perceptions of the social environment, and some research suggests that powerful individuals in particular tend to be lazy, disinterested observers of the social world. A handful of field studies and lab experiments linking power with individuals’ perceptions of others’ social networks have generally supported this view. However, recent theory addressing the psychological consequences of power for the power-holder claim that in certain circumstances and for some kinds of social information, power is linked to increased accuracy of social information. This dissertation tests this idea by drawing on social network theory and the situated focus theory of power. I examine the relationship between individuals’ formal power and their perceptual accuracy of social network relationships. I propose that individuals’ perceptual accuracy is affected by 1) their formal power in the organization 2) the type of relationship being perceived (expressive/instrumental, positive/negative), and 3) the dependence relationship with the target of perception (whether the perceiver is dependent on the perceived to get their work done). Predictions were tested using cognitive social network data collected from a call center within a division of a large corporation in the US. Results showed that formal power was linked to increased accuracy for some relationship content (particularly negative expressive relationships), and managers tend to be more accurate when perceiving their own incoming relationships than non-managers.

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In this thesis, ties and time-varying covariates in survival analysis are investigated. There are two types of ties: ties between event times (Type 1 ties) and ties between event times and the time that discrete time-varying covariates change or "jump"(Type 2 ties). The Cox proportional hazards model is one of the most important regression models for survival analysis. Methods for including Type 1 ties and time-varying covariates in the Cox proportional hazards model are well established in previous studies, but Type 2 ties have been ignored in the literature. This thesis discusses the effect of Type 2 ties on Cox's partial likelihood, the current default method to treat Type 2 ties in statistical packages SAS and R (called Fail before Jump in this thesis), and proposes alternative methods (Random and Equally Weighted) for Type 2 ties. A simulation study as well as an analysis of data sets from real research both suggest that both Random and Equally Weighted methods perform better than the other two methods. Also the effect of the percentages of Type 1 and Type 2 ties on these methods for handling both types of ties is discussed. / NSERC

Eine der zentralen Aufgaben der Geodäsie liegt in der Definition und der Realisierung von geeigneten Referenzsystemen. Die Realisierung eines globalen terrestrischen Referenzsystems wird als Referenzrahmen bezeichnet und ist durch Positionen zu einer Bezugsepoche und durch zeitlich lineare Bewegungen global verteilter Stationen festgelegt. Verschiedene Satellitenbeobachtungsverfahren können kombiniert werden, um ein globales terrestrisches Referenzsystem höchstmöglicher Genauigkeit, Stabilität und Konsistenz zu realisieren. Im Rahmen dieser Arbeit fanden dazu GPS- und GLONASS-Beobachtungen der Globalen Navigationssatellitensysteme (engl. Global Navigation Satellite System - GNSS) und Laserentfernungsmessungen (engl. Satellite Laser Ranging - SLR) zu den passiven Satelliten LAGEOS-1 und LAGEOS-2 Anwendung. Die Datengrundlage sind tägliche Normalgleichungssysteme für GNSS und wöchentliche für SLR über einen Zeitraum von 17 Jahren (1994 - 2010). Diese entstammen einer homogenen Reprozessierung, welche unter der Beteiligung der TU München, der Universität Bern, der ETH Zürich und der TU Dresden erfolgte. Dabei wurden Reduktionsmodelle verwendet, welche sich an den aktuellen IERS-Konventionen orientieren. Die verschiedenen Satellitenbeobachtungsverfahren wurden mit der gleichen wissenschaftlichen Software ausgewertet und kombiniert. Die Lösung weist daher eine höchstmögliche Konsistenz auf. In Anlehnung an die Empfehlungen in den aktuellen IERS-Konventionen wurden Auflastdeformationen infolge von Massenvariationen in der Atmosphäre und im Ozean im Auswerteprozess berücksichtigt. Dazu fand ein Modell Anwendung, welches schon bei der Reduktion von Beobachtungen der Schwerefeldmission GRACE (engl. Gravity Recovery and Climate Experiment) genutzt wird. Die Berücksichtigung dieses Modells führt zu einer Verbesserung der Genauigkeit der GNSS- und SLR-Stationspositionen. Da die SLR-Stationspositionen aufgrund eines systematischen Effektes (engl. blue sky effect) leicht verfälscht sind, sollte dieser Effekt berücksichtigt werden. Dies gilt vor allem vor dem Hintergrund einer Kombination der Verfahren zur Realisierung eines globalen terrestrischen Referenzsystems höchster Genauigkeit. Darüber hinaus überlagern weitere nichtlineare geophysikalische Effekte das lineare Modell aus Positionen und Geschwindigkeiten, z.B. die Auflastdeformation infolge kontinentaler Wasserspeicheränderungen. Werden diese Effekte in einer Auswertung nicht reduziert, sind in den ausgeglichenen Parametern sogenannte residuale Deformationen enthalten. Im Rahmen dieser Arbeit wurde daher das lineare Modell erweitert, indem residuale Deformationen in Form einer sphärisch harmonischen Entwicklung parametrisiert wurden. Die daraus bestimmten Grad-1-Auflastkoeffizienten weisen ein starkes jährliches Signal auf, welches sowohl die GNSS- als auch die SLR-Lösung zeigen. Die Kombination von GNSS und SLR erfolgte auf Normalgleichungsebene. Um die individuellen Stärken der Verfahren optimal ausnutzen zu können, wurden für eine gegenseitige Gewichtung der Verfahren realistische Genauigkeitsmaße abgeleitet. Es wurden Stationspositionen und -geschwindigkeiten geschätzt sowie die Polkoordinaten und die Grad-1-Auflastkoeffizienten gemeinsam ausgewertet. Im Gegensatz zu den bisherigen Referenzrahmen wurden keine terrestrisch gemessenen Differenzvektoren (engl. Local Ties - LT) an Kolokationsstationen verwendet, um die verfahrensinternen Lösungen zu kombinieren. Mit einer entsprechenden Definition des geodätischen Datums konnten hingegen Komponenten der LT als Unbekannte aus einer globalen Lösung bestimmt werden. Dies ermöglichte eine unabhängige Validierung der LT, welche einen entscheidenden Punkt in der Kombination unterschiedlicher Verfahren darstellen. / One of the main tasks of geodesy is the definition and realization of reference systems. A global terrestrial reference system is realized by a reference frame of a set of positions which respect to a reference epoch and linear motions of a network of globally distributed stations on the Earth's surface. Different space geodetic techniques can be combined to realize a reference system with optimal accuracy, stability and consistency. As such, the focus of this thesis was to apply GPS and GLONASS of the Global Navigation Satellite System (GNSS) and satellite laser ranging (SLR) to LAGEOS-1 and LAGEOS-2 to determine an improved global terrestrial reference frame. The data are daily for GNSS and weekly for SLR normal equation systems over a time span of 17 years (1994 - 2010), produced from a homogeneous reprocessing. This was done through a joint effort of TU Munich, University of Bern, ETH Zurich and TU Dresden using common state of the art reducing models according to the IERS conventions. The same processing software was used to evaluate and combine the different geodetic systems to ensure the highest consistency. Utilizing the recommendations of the IERS conventions 2010, the displacement of the Earth's surface due to mass variations in the atmosphere and in the ocean was reduced from the observations. A model of the non-tidal part which is also used for the reduction of observations of the geodetic gravity mission GRACE (Gravity Recovery and Climate Experiment) was applied. The reduction of this model enhances the position accuracy of the GNSS and SLR position time series. Because of the systematic effect on SLR observations (blue sky effect) the surface load deformation should be reduced especially when combining SLR and GNSS to realize a global terrestrial system. In addition there are more geophysical effects on the station positions, for example the deformation of the Earth's surface due to continental hydrological loading. If such effects are not considered in the estimation process of geodetic observations, residual deformations are present in the estimated parameters. Therefore, this effort included modeling of deformation in the solution by using a consistent spherical harmonic approach of degree-one surface load coefficients. The residual deformations such as hydrological loading modeled with degree-one surface load coefficients have a strong annual signal for which the GNSS-only and the SLR-only solutions show the same variations. The combination of GNSS and SLR was done at the level of normal equations. Considering the strengths of each technique, an optimal weighting based on more realistic uncertainties was applied to the data. The pole coordinates and the degree-one surface load coefficients were combined. Unique to the most recent realizations of a global terrestrial reference system, no local ties (LT) of co-located sites were used in the combination of the different techniques. Thus, using a global solution together with an appropriate definition of the geodetic datum of the combined station network it was possible to estimate components of LT. This estimation enables an independent validation of the measured LT which are a crucial point in combination of different geodetic techniques.

Cette thèse s'efforce de comprendre l'impact de multiples orientations stratégiques sur la performance de l'entreprise micro-familiale dans un contexte d’économie en développement, en trois phases distinctes. Tout d'abord, nous avons posé la question de savoir si les micro-entrepreneurs familiaux améliorent leur performance en développant simultanément des activités axées sur l'entrepreneuriat et sur le marché. Nous avons également étudié si ces orientations stratégiques complémentaires sur la performance sont favorisées par le capital social, sous forme de liens commerciaux et sociaux. En outre, nous avons soulevé une question sur l’effet de l’intervention de la famille sur la performance dans le contexte de multiples orientations stratégiques. L'étude initiale a fourni un thème de recherche fécond sur l'entreprise familiale dans un environnement institutionnel. Nous avons montré que les micro-entreprises familiales optimisent leurs performances commerciales en investissant dans des niveaux plus élevés d'orientation entrepreneuriale et commerciale. En outre, le processus de socialisation avec l’environnement commercial augmente la performance grâce aux effets combinés des orientations entrepreneuriale et de marché dans un contexte d’économies émergentes. Contrairement à ce que l’on pourrait penser, l'étude a révélé que la performance des entreprises augmente lorsque les deux orientations sont élevées, mais seulement lorsque l'engagement familial est faible. Ce résultat a permis d'améliorer la connaissance que l’on a de l'influence de la famille sur l'élaboration de comportements stratégiques pour atteindre une meilleure performance. L'étude subséquente, examine et révèle le côté sombre et lumineux de la famille en relation avec des stratégies d'orientation entrepreneuriale et de marché et son impact sur la performance. L'étude quantitative finale contredit la recherche antérieure révélant l'importance des capacités familiales dans le soutien des comportements à risque pour accroître la richesse familiale dans un contexte émergent. / This dissertation endeavors to understand the impact of multiple strategic orientations on the performance of the micro family business in developing economy settings in three distinct phases. First, we raised a question whether family micro-entrepreneurs gain performance benefits by developing simultaneously high levels of entrepreneurial-oriented and market-oriented activities. We also investigated whether these complementary strategic orientations on performance are rewarded by cultivating high levels of firm social capital in the form of business and social network ties. In addition, we raised a question how family fits together in the context of multiple strategic orientations to achieve superior performance. The initial study, therefore, yielded a rich research theme related to family business in the context of institutionally constrained environment. We have shown that micro family businesses do maximize their business performance by investing on higher levels of entrepreneurial and market orientation. Furthermore, firm socialization process with their external business entities increase the performance benefits by combined effects of entrepreneurial and market orientations in an emerging market setting. Contrary to conventional wisdom, the study revealed that business profitability increases when both orientations are high but only when family involvement is low. This result yielded important insights into the role of family influence in shaping firm strategic behaviors to achieve better performance. The subsequent study, therefore, reviews and revealed the dark and bright side of the family in combination with entrepreneurial and market orientation behaviors and its consequent impact on performance. The final quantitative study contradicts previous research finding revealing the importance of family-based capabilities in supporting risk-taking behaviors to increase family wealth in an emerging market setting.