David Krackhardt

David Krackhardt
Carnegie Mellon University | CMU · Heinz College of Public Policy & Management and Tepper School of Business

PhD

About

113
Publications
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19,126
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Introduction

Publications

Publications (113)
Article
This paper proposes that common measures for network transitivity, based on the enumeration of transitive triples, do not reflect the theoretical statements about transitivity they aim to describe. These statements are often formulated as comparative conditional probabilities, but these are not directly reflected by simple functions of enumerations...
Article
This paper explores the role of local structural conditions that facilitate or hinder violence when enmity is present between parties, by examining shooting-involved violence among street gangs in Long Beach, California. Using structural balance theory, this paper investigates whether certain triadic structures in which two rival gangs i and j are...
Article
Full-text available
This paper proposes that common measures for network transitivity, based on the enumeration of transitive triples, do not reflect the theoretical statements about transitivity they aim to describe. These statements are often formulated as comparative conditional probabilities, but these are not directly reflected by simple functions of enumerations...
Article
Methods: Measures were collected using archival shift records, workplace injury data, and cross-sectional surveys from a nationally representative sample of 14 EMS agencies employing paramedics, prehospital nurses, and other EMS clinicians. One thousand EMS clinicians were selected at random to complete a teamwork survey for each of their recent p...
Article
Objective: We investigated the association between teammate familiarity and workplace injury in the emergency medical services (EMS) setting. Methods: From January 2011 to November 2013, we abstracted a mean of 29 months of shift records and Occupational Safety Health Administration injury logs from 14 EMS organisations with 37 total bases locat...
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Although multiple disciplines have been applied to the study of organizations, organizational research is rarely interdisciplinary in the sense of two or more disciplines being linked in the joint analysis of organizational phenomena. The articles in this special issue illustrate the kinds of insights that can be gained by moving from a purely disc...
Article
Whereas recent research on organizational innovation suggests that there is an ecology of roles supporting the innovation process, the majority of network research has concentrated on the role of inventors. In this paper, we contribute to research on organizational innovation by studying the social structural conditions conducive to individuals sup...
Article
In a collaborative learning environment, transfer of knowledge depends strongly on sociocultural factors including the interaction among the learners as well as the interactions with the instructor. An understanding of some of the factors that affect the dynamics of learners and learning can be gleaned through the use of social network analysis (SN...
Article
We study the effect of peer influence in the diffusion of the iPhone 3G across a number of communities sampled from a large dataset from a major European Mobile carrier in one country. We identify tight communities of users in which peer influence may play a role and use instrumental variables to control for potential correlation between unobserved...
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We examine the effect of friendship in triads on retaliatory responses to unfair outcomes that originate from a group member. Drawing on Simmel's classic discussion of relationships in social triads versus dyads, we hypothesized that the effect of unfairness on retaliation between friends is stronger when the third party in the triad is a mutual fr...
Article
I assess the extent that the egonet method of collecting data permits accurate inferences to the true structural features of the network. This inference problem has three critical components: local-global inference error, ego distortion, and feature inference error. Analysis of four data sets indicates that structural features can be predicted by e...
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Objectives: We sought to test reliability of two approaches to classify adverse events (AEs) associated with helicopter EMS (HEMS) transport. Methods: The first approach for AE classification involved flight nurses and paramedics (RN/Medics) and mid-career emergency physicians (MC-EMPs) independently reviewing 50 randomly selected HEMS medical r...
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A collaborative nurse work environment is associated with ICU quality, yet collaborative interaction is difficult to measure. Network analysis may be an innovative tool to measure interactions. We sought to determine the feasibility of network analysis to measure ICU nurse connectivity and test whether key network measures were associated with the...
Chapter
In this chapter, we develop a framework for understanding how multidimensional, multilevel data is most effectively conveyed in social network diagrams. We build on work begun in 1994, with a series of explorations of social network visualization with the theme of helping viewers make accurate judgments about network properties. In contrast to cont...
Article
Lack of familiarity between teammates is linked to worsened safety in high risk settings. The emergency department (ED) is a high risk healthcare setting where unfamiliar teams are created by diversity in clinician shift schedules and flexibility in clinician movement across the department. We sought to characterise familiarity between clinician te...
Article
This paper aims to further our understanding of how embeddedness affects the research output and impact of scientists. The analysis uses an extensive panel data that allows an analysis of within person variation over time. It explores the simultaneous effects of different dimensions of network embeddedness over time at individual level. These inclu...
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Background The Emergency Department (ED) is consistently described as a high-risk environment for patients and clinicians that demands colleagues quickly work together as a cohesive group. Communication between nurses, physicians, and other ED clinicians is complex and difficult to track. A clear understanding of communications in the ED is lacking...
Article
Cohesion and structural equivalence are two competing network models to explain diffusion of innovation. The dispute of which model plays a more influential role has not been resolved. This paper attempts to reconcile this problem in a large network setting - adoption of caller ringback tone (CRBT) in a cellular telephone conversation network. Sinc...
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The rise of socially targeted marketing suggests that decisions made by consumers can be predicted not only from their personal tastes and characteristics, but also from the decisions of people who are close to them in their networks. One obstacle to consider is that there may be several different measures for "closeness" that are appropriate, eith...
Article
This paper studies the effects of peer influence and homophily on the diffusion of the iPhone 3G across a number of communities sampled from a large dataset from a major European Mobile carrier in one country. We use Stochastic Actor Based Models to capture the co-evolution of the social network as well as the dynamics of adoption. This helps to se...
Article
This paper studies the effect of peer influence on the diffusion of the iPhone 3G across a number of communities sampled from a large dataset from a major European Mobile (EURMO) carrier in one country. We use instrumental variables to control for potential correlation between unobserved subscriber heterogeneity and peer influence. We provide evide...
Article
Full-text available
The rise of socially targeted marketing suggests that decisions made by consumers can be predicted not only from their personal tastes and characteristics, but also from the decisions of people who are close to them in their networks. One obstacle to consider is that there may be several different measures for "closeness" that are appropriate, eith...
Article
Krackhardt (1994) proposed four dimensions to describe and measure the amount of hierarchy in networks of informal organizations. We examine these conditions, suggest some relaxations and prove that they are both necessary and sufficient to guarantee an arborescence (or out-tree). In addition we suggest situations some of which are outside of infor...
Article
In this paper we analyze a large-scale comprehensive dataset from a major European Mobile Phone Provider (EURMO). This dataset allows us to study the diffusion of the iPhone 3G. We provide evidence of contagious adoption. We show that the propensity for iPhone 3G adoption increases with the number of individuals within the social network that have...
Article
Cohesion and structural equivalence are two competing social network models to explain diffusion of innovation. While considerable work has been done on these models, the question of which network model explains diffusion has not been resolved. This paper examines adoption of Caller Ring Back Tones (CRBT) in a cellular telephone conversation networ...
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Full-text available
We sought to develop a reliable and valid tool for measuring teamwork among emergency medical technician (EMT) partnerships. We adapted existing scales and developed new items to measure components of teamwork. After recruiting a convenience sample of 39 agencies, we tested a 122-item draft survey tool (EMT-TEAMWORK). We performed a series of explo...
Article
The purpose of this study was to develop a method to define and rate the severity of adverse events (AEs) in emergency medical services (EMS) safety research. They used a modified Delphi technique to develop a consensus definition of an AE. The consensus definition was as follows: "An adverse event in EMS is a harmful or potentially harmful event o...
Article
To characterize patterns of Emergency Medical Technician (EMT) partner familiarity in three Emergency Medical Services (EMS) agencies. STUDY DESIGN/DATA SOURCES: We utilized a case study design and retrospective review of administrative data from three EMS agencies and 182 EMTs over 12 months. We used the Kruskal-Wallis test and Bonferroni correcte...
Article
This paper explores what system factors influenced the adoption of Family Group Decision Making (FGDM) in Pennsylvania and what the perceived barriers and facilitators of adoption and sustainability are according to the individuals involved in FGDM. A mixed methods design is employed, using geographic autocorrelation modeling and analysis of qualit...
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a b s t r a c t The literature on social networks and their analysis has undergone explosive growth in the past decade. Network models have been used to study structures as diverse as the interaction of monks in a monastery, the links across the World Wide Web, and the structure of organizations. In much of this literature the network itself is vie...
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To study how social interactions influence physician adoption of an electronic health records (EHR) system. A social network survey was used to delineate the structure of social interactions among 40 residents and 15 attending physicians in an ambulatory primary care practice. Social network analysis was then applied to relate the interaction struc...
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In this article, we study the conditions under which having ties that span organizational boundaries (bridging ties) are conducive to the generation of innovations. Whereas previous research has shown that bridging ties have a positive impact on innovative performance, our analysis of 276 R&D scientists and engineers reveals that there are no advan...
Article
This paper examines the relationship between the social capital and knowledge creation in research, mostly in the context of universities. The analysis is developed considering all of the following critical aspects of social capital: direct ties, strengths of direct ties, density, structural holes, centrality, and external-internal index in terms o...
Chapter
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Heider’s balance theory is ubiquitous in the field of social networks as an explanation for why we so frequently observe symmetry and transitivity in social relations. We propose that Simmelian tie theory could explain the same phenomena without resorting to motivational tautologies that characterize psychological explanations. Further, while both...
Article
Given the complexity of organizing and keeping track of even a small organizational network, boundedly rational people may have learned to use small world principles in perceiving friendship networks: arrange people in dense clusters, and connect the clusters with short paths. Analysis of 116 perceived friendship networks from four different organi...
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Multiple regression quadratic assignment procedures (MRQAP) tests are permutation tests for multiple linear regression model coefficients for data organized in square matrices of relatedness among n objects. Such a data structure is typical in social network studies, where variables indicate some type of relation between a given set of actors. We p...
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An analysis is conducted on the robustness of measures of centrality in the face of random error in the network data. We use random networks of varying sizes and densities and subject them (separately) to four kinds of random error in varying amounts. The types of error are edge deletion, node deletion, edge addition, and node addition. The results...
Article
The objective was to determine whether obstetric opinion leaders can be identified and to characterize them in terms of their demographic and professional characteristics and their attitudes toward caesarean delivery. In late 1998, we surveyed 527 obstetricians, 138 family physicians, and 80 certified nurse midwives (overall response rate, 57.8%) p...
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Understanding the overall network structure of organizations can help managers to support change. This article describes three different network theories of change, exploring the underlying assumptions and implications of each model. First, the E-I model predicts that cross-departmental friendship ties will help generate positive response to change...
Article
This article develops a cultural agreement approach to organizational culture that emphasizes how clusters of individuals reinforce potentially idiosyncratic understandings of many aspects of culture including the structure of network relations. Building on recent work concerning Simmelian tied dyads (defined as dyads embedded in three-person cliqu...
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Changes in relationships are due to human actions. We assume that these human actions are functions of perceptions of a focal individual, but also the perceptions of other individuals who are part of the organizational and social environment. We hypothesize that perceptions based trust and perceptions of the structural environment individuals opera...
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In this paper we focus on the question how interpersonal network structures affect the degree of organization wide knowledge utilization. Coordinating the balance between knowledge utilization and knowledge generation is important for organizations (cf. March, 1991). Organizational structures that coordinate this balance can be characterized by peo...
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We propose a two-stage MRQAP to analyze dynamic network data, within the framework of an equilibrium-correction (EC) model. Extensive simulation results indicate practical relevance of our method and its improvement over standard OLS. An empirical illustration additionally shows that the EC model yields interpretable parameters, in contrast to an u...
Article
This paper shows that Medical Innovation (Coleman, Katz and Menzel 1966) and several subsequent studies analyzing the diffusion of the drug tetracycline have confounded social contagion with marketing effects. First, we describe the medical community's understanding of tetracycline and how the drug was marketed at the time the Medical Innovation da...
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The fundamental empirical structural balance hypothesis claims that human signed networks tend towards balance over time. Balance theorists assume that there is a balance theoretic mechanism whose cumulative effect drives the evolution of signed social structures towards balance. In previous work, we used a line index of imbalance to measure the im...
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This paper shows how two different theoretical approaches to model innovation adoption, network threshold modeling and random utility modeling, both result in discrete-time hazard models, a popular statistical modeling approach to study innovation adoption and diffusion. The paper emphasizes the need for careful situational analysis prior to model...
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We show how one can specify micro-level hazard models of adoption that separately represent the awareness and evaluation/choice stage of the adoption decision process even when one observes only the final outcome, i.e. adoption or not. These models can be derived from random utility theory. Using a small simulation study, we show that the two-stage...
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This paper uses three-way and sociometric data to reconstitute individual conceptions of peer-driven intervention for the protection of common resources in a collegial organization, a Northeastern corporate law firm. Variations in partners'' individual conceptions are explained in terms of management of costs of lateral control. Costs of control ar...
Article
This study explores one of the contributors to group composition—the basis on which people choose others with whom they want to work. We use a combined model to explore individual attributes, relational attributes, and previous structural ties as determinants of work partner choice. Four years of data from participants in 33 small project groups we...
Article
Network researchers have argued that both relational embeddedness—characteristics of relationships—and structural embeddedness—characteristics of the relational structure—influence firm behavior and performance. Using strategic alliance networks in the semiconductor and steel industries, we build on past embeddedness research by examining the inter...
Article
Network researchers have argued that both relational embeddedness—characteristics of relationships—and structural embeddedness—characteristics of the relational structure—influence firm behavior and performance. Using strategic alliance networks in the semiconductor and steel industries, we build on past embeddedness research by examining the inter...
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Sumario: Many executives invest considerable resources in restructuring their companies, drawing and redrawing organizational charts only to be disappointed by the results. That's because much of the real work of companies happens despite the formal organization. Often what needs attention is the informal organization, the networks of relationships...
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We investigated how positive affectivity influences people's perception of the patterns of social relationships around them. Positive affectivity was measured as trait positive affect. The outcome variable was accuracy in the perception of informal patterns of social interaction in a group (i.e., the group's network structure). Data on the percepti...
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Under what circumstances are individuals' perceptions of friendship relations shaped by the balance schema? Using data from 4 organizations varying in size from 21 to 33 members, the authors investigated how ego's perception of the social distance from ego to alter affected the proportion of alter's friendships perceived by ego as balanced. Balance...
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The abstract for this document is available on CSA Illumina.To view the Abstract, click the Abstract button above the document title.
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L'auteur tente de montrer comment la methode statistique utilisee en recherche medicale et connue sous le nom de test de Mantel peut etre utilisee pour analyser les hypotheses de reseaux en archeologie.
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We present a network based approach to characterize organizational architectures in terms of three domain elements - individuals, tasks, and resources. Characterizing the possible relations among these elements results in five relational primitives - Precedence, Commitment of resources, Assignment of individuals to tasks, Networks (of relations amo...
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This paper draws on the biological work of Boorman and Levitt's Genetics of Altruism to develop a model of diffusion in organizations specifically when the innovation being diffused is controversial. By “controversial”, I mean an innovation whose value (and subsequent adoption) is socially determined and not rationally determined ‐ that is, there i...
Article
The spatial arrangement of social network data in graphs can influence viewers' perceptions of structural characteristics such as prominence, bridging and grouping. To study the extent of this effect, we conducted an experiment with 80 graduate students. Each student viewed three of five different spatial arrangements of the same network. We found...
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In this article, the authors examine the social conditions experienced by Asian employees in the workforce, focusing in particular on the lower returns to education that have been documented for both immigrant and U.S.-born Asians. The authors suggest that human capital translates into improved career outcomes by producing greater social capital an...
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Numerous measures of organizational structure have been developed. The goal is to develop a small meaningful and predictive set. Work in this area, however, has been hampered by a lack of a standard categorization schema. Such a schema is presented herein. This schema is based on the recognition that many aspects of organizational structures can be...
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We present methods for establishing the amount of reciprocity, transitivity and group balance (a generalization of structural balance) in sociometric structures. These methods are applied to the second time series of sociometric data provided by the Newcomb (1961) study. The amount of reciprocity was above chance levels at the outset and showed no...
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Article
Non-reciprocated relationships, such as all workers knowing the president of the company but only a few of the workers being known by the president, and non-symmetric relationships, such as workers thinking that they know the president and thinking that the president does not know them, are endemic to most social situations. While such inconsistenc...