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Computational Social Science:

  1. A. M. Petersen
    University digital media co-occurrence networks reveal structure and dynamics of brand visibility in the attention economy (pdf)
    Under review, (2024). Abstract As universities compete for visibility to attract student enrollment and build scientific reputation, the management of institution of higher education (IHE) brand has emerged as an important strategic endeavor. Yet our understanding of the factors that condition the structure and dynamics of brand stratification within regional IHE ecosystems is limited. Instead, our best approximation for brand equity derives from widespread IHE rankings, which lack contextual and relational features for understanding the patterns of engagement in the fast-moving attention economy, and in particular how institutional partnerships can generate brand equity by leveraging ecosystem network effects. To this end, here we develop a framework for measuring two dimensions of brand equity, namely visibility and association, according to the frequency of digital media articles featuring a university's official name. We demonstrate this approach for 29 universities in California and Texas based upon 2 million media articles published between 2000-2020, and validate our approach by correlating university digital media visibility with ARWU Shanghai rankings and freshman enrollment growth. As roughly 10% of the article sample features >1 university, longitudinal analysis of institutional co-occurrence reveals the extent to which brand association stratifies according to regional proximity, institutional specialization and prestige. Interestingly, despite the shared value generated from media co-visibility, the frequency of multi-university media articles has declined over time, which we attribute to paradigm shifts in media content production following the 2007-08 financial crisis and the COVID-19 infodemic, in addition to increased competitiveness of the attention economy. Topic classification of media article titles shows how specialized institutions may strategically manage their brand equity by aligning content production with dominant media topics to reinforce brand visibility with broader social, technological and environmental narratives.

  2. F. Arroyave, J. Jenkins, A. M. Petersen
    Network embedding for understanding the National Park System through the lenses of news media, scientific communication and biogeography (pdf)
    Annals of the American Association of Geographers (2023). DOI:10.1080/24694452.2023.2277808 Abstract The U.S. national parks encompass a variety of biophysical and historical resources important for national cultural heritage. Yet how these resources are socially constructed often depends upon the beholder. Parks tend to be conceptualized according to their (fixed) geographic context, so our understanding of this system of systems is dominated by this geographic lens. To expose the systemic structure that exists beyond their geographic embedding, we analyze three representations of the national park system using park-park similarity networks according to their co-occurrence in: (a) ~423,000 news media articles; (b) ~11,000 research publications; and (c) ~60,000 species inhabiting parks. We quantify structural variation between network representations leveraging similarity measures at different scales: park-level (park-park correlations) and system-level (network communities’ consistency). Because parks are governed and experienced at multiple scales, cross-network comparison informs how management should account for the varying objectives and constraints that dominate at each scale. Our results identify an interesting paradox: whereas park-level correlations depend strongly on the representative lens, the network communities are remarkably robust and consistent with the underlying geographic embedding. Overall, our data-driven methodology is generalizable to other geographically embedded systems and supports the holistic analysis of systems-level structure that may elude other approaches.
    -How Scientific Research Can Inform Visitor and Environmental Management at National Parks, UC Merced Newsroom, Patty Guerra,

  3. A. M. Petersen
    How much did pandemic uncertainty affect real-estate speculation? Evidence from on-market valuation of For-Sale versus Rental properties (pdf)
    In press, Applied Economics Letters (2024). DOI:10.1080/13504851.2024.2302898 Abstract We exploit a panel of Zillow Inc. property valuations to estimate the excess real-estate price growth observed in three California cities that is attributable to speculation triggered by the COVID-19 pandemic. Our research design leverages the counterfactual comparison of properties listed for sale to properties listed for rent, with the latter property class being available for habitation – just not for purchase – and thus neutral to price speculation. We implement a pre/post-2020 difference-in-difference estimation, which utilizes unit-level matching of otherwise similar sale and rental properties within a 1/2-mile radius of each other to compare differences in: (a) 1-month valuation changes; and (b) spot valuation uncertainties. Results indicate post-2020 property valuations in Merced and San Jose featured an excess annual price estimate growth of 22 and 14.8 percentage points, respectively, whereas the Fresno market does not feature statistically significant excess growth.

  4. A. M. Petersen
    Shift in house price estimates during COVID-19 reveals effect of crisis on collective speculation (pdf)
    EPJ Data Science 13, 47 (2024). DOI:10.1140/epjds/s13688-024-00488-9 Abstract We exploit a timely city-level panel of individual house price estimates for both small and big real-estate markets in California USA to estimate the impact of COVID-19 on the housing market. Descriptive analysis of spot house price estimates, including contemporaneous price uncertainty and 30-day price change for individual properties listed on the online real-estate platform Zillow.com, together facilitate quantifying both the excess valuation and valuation confidence attributable to this global socio-economic shock. Our quasi-experimental pre-/post-COVID-19 design spans several years around 2020 and leverages contemporaneous price estimates of rental properties – i.e., real estate entering the habitation market, just not for purchase and hence free of speculation – as an appropriate counterfactual to properties listed for sale. Combining unit-level matching and difference-in-difference approaches, we estimate that properties listed for sale after the pandemic featured an excess monthly price growth of roughly 1 percentage points, corresponding to an excess annual price growth of roughly 12.7 percentage points, which accounts for more than half of the annual growth observed across those regions in 2021. Simultaneously, uncertainty in price estimates decreased, signaling the irrational confidence characteristic of prior asset bubbles. We explore how these two trends are related to market size, local market supply and borrowing costs, which altogether lend support for the counter-intuitive roles of uncertainty and interruptions in decision-making.

  5. D. Yang, I. Pavlidis, A. M. Petersen
    Biomedical convergence facilitated by the emergence of technological and informatic capabilities (pdf)
    Advances in Complex Systems 26, 2350003 (2023). DOI:10.1142/S0219525923500030 Abstract We analyzed Medical Subject Headings (MeSH) from 21.6 million research articles indexed by PubMed to map this vast space of entities and their relations, providing insights into the origins and future of biomedical convergence. Detailed analysis of MeSH co-occurrence networks identifies three robust knowledge clusters: the vast universe of microscopic biological entities and structures; systems, disease and diagnostics; and emergent biological and social phenomena underlying the complex problems driving the health, behavioral and brain science frontiers. These domains integrated from the 1990s onward by way of technological and informatic capabilities that introduced highly controllable, scalable and permutable research processes and invaluable imaging techniques for illuminating fundamental structure-function-behavior questions. Article-level analysis confirms a positive relationship between team size and topical diversity, and shows convergence to be increasing in prominence but with recent saturation. Together, our results invite additional policy support for cross-disciplinary team assembly to harness transdisciplinary convergence.
    - Funded by NSF award #1738163
    - Presented at the 2024 Science of Team Science conference (INSciTS): Video Summary

  6. A. M. Petersen, M. E. Ahmed, I. Pavlidis
    Grand challenges and emergent modes of convergence science (pdf)    (Supporting Information)
    Nature Humanities and Social Sciences Communications 8, 194 (2021). DOI:10.1057/s41599-021-00869-9 Abstract To address complex problems, scholars are increasingly faced with challenges of integrating diverse knowledge domains. We analyzed the evolution of this convergence paradigm in the broad ecosystem of brain science, which provides a real-time testbed for evaluating two modes of cross-domain integration – subject area exploration via expansive learning and cross-disciplinary collaboration among domain experts. We show that research involving both modes features a 16% citation premium relative to a mono-disciplinary baseline. Further comparison of research integrating neighboring versus distant research domains shows that the cross-disciplinary mode is essential for integrating across relatively large disciplinary distances. Yet we find research utilizing cross- domain subject area exploration alone – a convergence shortcut – to be growing in prevalence at roughly 3% per year, significantly faster than the alternative cross-disciplinary mode, despite being less effective at integrating domains and markedly less impactful. By measuring shifts in the prevalence and impact of different convergence modes in the 5-year intervals before and after 2013, our results indicate that these counterproductive patterns may relate to competitive pressures associated with global Human Brain flagship funding initiatives. Without additional policy guidance, such Grand Challenge flagships may unintentionally incentivize such convergence shortcuts, thereby undercutting the advantages of cross-disciplinary teams in tackling challenges calling on convergence.
    - Funded by NSF award #1738163
    - Presented at ICCSI 2022 hosted by the US National Academy of Sciences: Full Poster & Video Summary

  7. F. J. Arroyave, A. M. Petersen, J. Jenkins, R. G. Hurtado
    Multiplex networks reveal geographic constraints on illicit wildlife trafficking (pdf)
    Applied Network Science 5, 20 (2020). DOI:10.1007/s41109-020-00262-6 Abstract Illicit wildlife trafficking poses a threat to the conservation of species and ecosystems, and represents a fundamental source of biodiversity loss, alongside climate change and large-scale land degradation. Despite the seriousness of this issue, little is known about various socio-cultural demand sources underlying trafficking networks, for example the forthright consumption of endangered species on different cultural contexts. Our study illustrates how wildlife trafficking represents a wicked problem at the intersection of criminal enforcement, cultural heritage and environmental systems management. As with similar network-based crimes, institutions are frequently ineffective at curbing wildlife trafficking, partly due to the lack of information detailing activities within illicit trading networks. To address this shortcoming, we leverage official government records documenting the illegal trade of reptiles in Colombia. As such, our study contributes to the understanding of how and why wildlife trafficking persists across robust trafficking networks, which are conduits for a broader range of black-market goods. Leveraging geo-spatial data, we construct a multiplex representation of wildlife trafficking networks, which facilitates identifying network properties that are signatures of strategic trafficker behavior. In particular, our results indicate that traffickers’ actions are constrained by spatial and market customs, a result which is apparent only within an integrated multiplex representation. Characteristic levels of sub-network coupling further indicate that traffickers strategically leverage knowledge of the entire system. We argue that this multiplex representation is essential for prioritizing crime enforcement strategies aimed at disrupting robust trade networks, thereby enhancing the effectiveness and resources allocation of institutions charged with curbing illicit trafficking. We develop a generalizable model of multiplex criminal trade networks suitable for communicating with policy makers and practitioners, thereby facilitating rapid translation into public policy and environmental conservation efforts.

  8. A. M. Petersen, O. Penner
    Renormalizing individual performance metrics for cultural heritage management of sports records (pdf)    (Pre-print OA Version)
    Chaos, Solitons & Fractals 136, 109821 (2020). DOI:10.1016/j.chaos.2020.109821 Abstract Individual performance metrics are commonly used to compare players from different eras. However, such cross-era comparison is often biased due to significant changes in success factors underlying player achievement rates (e.g. performance enhancing drugs and modern training regimens). Such historical comparison is more than fodder for casual discussion among sports fans, as it is also an issue of critical importance to the multi- billion dollar professional sport industry and the institutions (e.g. Hall of Fame) charged with preserving sports history and the legacy of outstanding players and achievements. To address this cultural heritage management issue, we report an objective statistical method for renormalizing career achievement metrics, one that is particularly tailored for common seasonal performance metrics, which are often aggregated into summary career metrics - despite the fact that many player careers span different eras. Remarkably, we find that the method applied to comprehensive Major League Baseball and National Basketball Association player data preserves the overall functional form of the distribution of career achievement, both at the season and career level. As such, subsequent re-ranking of the top-50 all-time records in MLB and the NBA using renormalized metrics indicates reordering at the local rank level, as opposed to bulk reordering by era. This local order refinement signals time-independent mechanisms underlying seasonal and cumulative achievement in professional sports, meaning that appropriately renormalized achievement metrics can be used to compare players from eras with different season lengths, team strategies, rules - and possibly even different sports.

  9. D. Majeti, E. Akleman, M. E. Ahmed, A. M. Petersen, B. Uzzi, I. Pavlidis
    Scholar Plot: Design and Evaluation of an Information Interface for Faculty Research Performance (pdf)
    Frontiers in Research Metrics and Analytics 4, 6 (2020). DOI:10.3389/frma.2019.00006 Abstract The ability to objectively assess academic performance is critical to rewarding academic merit, charting academic policy, and promoting science. Quintessential to performing these functions is first the ability to collect valid and current data through increasingly automated online interfaces. Moreover, it is crucial to remove disciplinary and other biases from these data, presenting them in ways that support insightful analysis at various levels. Existing systems are lacking in some of these respects. Here we present Scholar Plot (SP), an interface that harvests bibliographic and research funding data from online sources. SP addresses systematic biases in the collected data through nominal and normalized metrics. Eventually, SP combines synergistically these metrics in a plot form for expert appraisal, and an iconic form for broader consumption. SP’s plot and iconic forms are scalable, representing equally well individual scholars and their academic units, thus contributing to consistent ranking practices across the university organizational structure. In order to appreciate the design principles underlying SP, in particular the informativeness of nominal versus normalized metrics, we also present the results of an evaluation survey taken by senior faculty (n=28) with significant promotion and tenure assessment experience.
    - Funded by NSF award #1738163

  10. A. M. Petersen
    Megajournal mismanagement: Manuscript decision bias and anomalous editor activity at PLOS ONE (pdf)
    J. Informetrics 13, 100974 (2019). DOI:10.1016/j.joi.2019.100974 Abstract Since their emergence just a decade ago, nearly 2% of scientific research is now published by megajournals, representing a major industrial shift in the production of knowledge. Such high-throughput production stresses several aspects of the publication process, including the editorial oversight of peer-review. As the largest mega- journal, PLOS ONE has relied on a single-tier editorial board comprised of ∼7,000 active academics, who thereby face conflicts of interest relating to their dual roles as both producers and gatekeepers of peer-reviewed literature. While such conflicts of interest are also a factor for editorial boards of smaller journals, little is known about how the scalability of megajournals may introduce perverse incentives for editorial service. To address this issue, we analyzed the activity of PLOS ONE editors over the journal’s inaugural decade (2006-2015) and find highly variable activity levels. We then leverage this variation to model how editorial bias in the manuscript decision process relates to two editor-specific factors: repeated editor-author interactions and shifts in the rates of citations directed at editors – a form of citation remuneration that is analogue to self-citation. Our results indicate significantly stronger manuscript bias among a relatively small number of extremely active editors, who also feature relatively high self-citation rates coincident in the manuscripts they handle. These anomalous activity patterns are consistent with the perverse incentives and the temptations they offer at scale, which is the- oretically grounded in the "slippery-slope" evolution of apathy and misconduct in power-driven environments. By applying quantitative evaluation to the gatekeepers of scientific knowledge, we shed light on various ethics issues crucial to science policy – in particular, calling for more transparent and structured management of editor activity in megajournals that rely on active academics.
    -Personal biases speed up research publication: Megajournal editors under the microscope, Nature Index, Gemma Conroy
    -Analysis of highly prolific Plos One editors finds evidence for 'editor-author backscratching', Times Higher Education, Jack Grove
    -Editors secured citation bump, Science, Jeffrey Brainard

  11. A. M. Petersen, E. M. Vincent, A. L. Westerling
    Discrepancy in scientific authority and media visibility of climate change scientists and contrarians (pdf)    (Supporting Information)    (Addendum)
    Nature Communications 10, 3502 (2019). DOI:10.1038/s41467-019-09959-4 Abstract We juxtapose 386 prominent contrarians with 386 expert scientists by tracking their digital footprints across ∼200,000 research publications and ∼100,000 English-language digital and print media articles on climate change. Projecting these individuals across the same backdrop facilitates quantifying disparities in media visibility and scientific authority, and identifying organization patterns within their association networks. Here we show via direct comparison that contrarians are featured in 49% more media articles than scientists. Yet when comparing visibility in mainstream media sources only, we observe just a 1% excess visibility, which objectively demonstrates the crowding out of professional mainstream sources by the proliferation of new media sources, many of which contribute to the pro- duction and consumption of climate change disinformation at scale. These results demon- strate why climate scientists should increasingly exert their authority in scientific and public discourse, and why professional journalists and editors should adjust the disproportionate attention given to contrarians.
    -Media Creates False Balance on Climate Science, Study Shows, UC Communications, Lorena Anderson
    -U.S. Media gives way too much air time to climate change deniers who don't know what they're talking about, study finds, Newsweek, Hannah Osborne
    -Climato-scepticisme et médias : la duperie, Le Monde, Sylvestre Huet
    -Climate Deniers Receive More Media Attention Than Climate Scientists — Research, Desmog UK, Sophie Yeo
    -How open access extends the conversation around climate change in the era of fake news, Springer Nature, Roza Sakellaropoulou

  12. A. M. Petersen
    Multiscale Impact of Researcher Mobility (pdf)    (Supporting Information)
    Journal of the Royal Society Interface 15, 20180580 (2018). DOI:10.1098/rsif.2018.0580 Abstract International mobility facilitates the exchange of scientific, institutional and cultural knowledge. Yet whether globalization and advances in virtual communication technologies have altered the impact of researcher mobility is a relevant and open question that we address by analysing a broad international set of 26,170 physicists from 1980 to 2009, focusing on the 10-year period centred around each mobility event to assess the impact of mobility on research outcomes. We account for secular globalization trends by splitting the analysis into three periods, measuring for each period the effect of mobility on researchers' citation impact, research topic diversity, collaboration networks and geographical coordination. In order to identify causal effects we leverage statistical matching methods that pair mobile researchers with non-mobile researchers that are similar in research profile attributes prior the mobility event. We find that mobile researchers gain up to a 17% increase in citations relative to their non-mobile counterparts, which can be explained by the simultaneous increase in their diversity of co-authors, topics and geographical coordination in the period immediately following migration. Nevertheless, we also observe that researchers completely curtail prior collaborations with their source country in 11% of the cross-border mobility events. As such, these individual-level perturbations fuel multiscale churning in scientific networks, e.g. rewiring the connectivity of individuals and ideas and affecting international integration. Together these results provide additional clarity on the complex relationship between human capital mobility and the dynamics of social capital investment, with implications for immigration and national innovation system policy.
    -Why you should move country, Nature, Virginia Gewin
    -Considering going abroad for work?, Science, Elisabeth Pain
    -Physicists who move abroad can receive a 17% uplift in citations, study reveals, Physics World, Michael Allen
    -Migration brings citations boost, Science, Warren Cornwall

  13. A. M. Petersen, D. Majeti, K. Kwon, M. E. Ahmed, I. Pavlidis
    Cross-disciplinary evolution of the genomics revolution (pdf)    (Supporting Information)
    Science Advances 4(8), eaat4211 (2018). DOI:10.1126/sciadv.aat4211 Abstract Born out of the Human Genome Project (HGP), the field of genomics evolved with phenomenal speed into a dominant scientific and business force. While other efforts were intent on estimating the economic impact of the genomics revolution, we shift focus to the social and cultural capital generated by bridging together biology and computing - two of the constitutive disciplines of "genomics". We quantify this capital by measuring the pervasiveness of bio-computing cross-disciplinarity (XD) in genomics research during and after the HGP. To provide interlocking perspectives at the career and epistemic levels, we assembled three data sets to measure XD via (i) the collaboration network between 4190 biology and computing faculty from 155 departments in the United States, (ii) cross-departmental affiliations within a comprehensive set of human genomics publications, and (iii) the application of computational concepts and methods in research published in a preeminent genomics journal. Our results show the following: First, research featuring XD collaborations has higher citation impact than other disciplinary research - an effect observed at both the career and individual article levels. Second, genomics articles featuring XD methods tend to have higher citation impact than epistemically pure articles. Third, XD researchers of computing pedigree are drawn to the biology culture. This statistical evidence acquires deeper meaning when viewed against the organizational and knowledge transfer mechanisms revealed by the data models. With cross-disciplinary initiatives set to dominate the agenda of funding agencies, our case study provides a framework for appreciating the long-term effects of these initiatives on science and its standard-bearers.
    -How gene hunting changed the culture of science, EurekAlert! / CPLab Univ. Houston
    - Funded by NSF award #1738163

  14. R. K. Pan, A. M. Petersen, F. Pammolli, S. Fortunato
    The Memory of Science: Inflation, Myopia, and the Knowledge Network (pdf)
    J. Informetrics 12, 656-678 (2018). DOI:10.1016/j.joi.2018.06.005 Abstract Scientific production is steadily growing, exhibiting 4% annual growth in publications and 1.8% annual growth in the number of references per publication, together producing a 12-year doubling period in the total supply of references, i.e. links in the science citation network. This growth has far-reaching implications for how academic knowledge is connected, accessed and evaluated. Against this background, we analyzed a citation network comprised of 837 million references produced by 32.6 million publications over the period 1965-2012, allowing for a detailed analysis of the 'attention economy' in science. Our results show how growth relates to 'citation inflation', increased connectivity in the citation network resulting from decreased levels of uncitedness, and a narrowing range of attention - as both very classic and very recent literature are being cited increasingly less. The decreasing attention to recent literature published within the last 6 years suggests that science has become stifled by a publication deluge destabilizing the balance between production and consumption. To better understand these patterns together, we developed a generative model of the citation network, featuring exponential growth, the redirection of scientific attention via publications' reference lists, and the crowding out of old literature by the new. We validate our model against several empirical benchmarks, and then use perturbation analysis to measure the impact of shifts in citing behavior on the synthetic system's properties, thereby providing insights into the functionality of the science citation network as an infrastructure supporting the memory of science.
    -The growth of papers is crowding out old classics, Nature Index, Gemma Conroy

  15. O. A. Doria Arrieta, F. Pammolli, A. M. Petersen
    Quantifying the negative impact of brain drain on the integration of European science (pdf)    (Supporting Information)
    Science Advances 3(4), e1602232 (2017). DOI:10.1126/sciadv.1602232 Abstract The 2004/2007 European Union (EU) enlargement by 12 member states offers a unique opportunity to quantify the impact of EU efforts to expand and integrate the scientific competitiveness of the European Research Area (ERA). We apply two causal estimation schemes to cross-border collaboration data extracted from millions of academic publications from 1996 to 2012, which are disaggregated across 14 subject areas and 32 European countries. Our results illustrate the unintended consequences following the 2004/2007 enlargement, namely, its negative impact on cross-border collaboration in science. First, we use the synthetic control method to show that levels of European cross-border collaboration would have been higher without EU enlargement, despite the 2004/2007 EU entrants gaining access to EU resources incentivizing cross-border integration. Second, we implement a difference-in-difference panel regression, incorporating official intra-European high-skilled mobility statistics, to identify migration imbalance - principally from entrant to incumbent EU member states - as a major factor underlying the divergence in cross-border integration between Western and Eastern Europe. These results challenge central tenets underlying ERA integration policies that unifying labor markets will increase the international competitiveness of the ERA, thereby calling attention to the need for effective home-return incentives and policies.
    -Study Identifies Effects of EU Expansion on Labor, Research, UC Merced Communications, Lorena Anderson
    -Europe's paradox: Why increased scientific mobility has not led to more international collaborations, Science, Erik Stokstad
    -Joining the European Union leads to less cross-border collaboration, Nature, Daniel Cressy
    -EU Expansion did not Increase Cross-Border Research, AAAS, Megan Jula
    -The EU Had a Scientific Collaboration Problem Long Before Brexit, Motherboard, Ben Sullivan

  16. A. M. Petersen, M. Puliga
    High-skilled labour mobility in Europe before and after the 2004 enlargement (pdf)    (Supporting Information)
    Journal of the Royal Society Interface 14, 20170030 (2017). DOI:10.1098/rsif.2017.0030 Abstract The extent to which international high-skilled mobility channels are forming is a question of great importance in an increasingly global knowledge-based economy. One factor facilitating the growth of high-skilled labor markets is the standardization of certifiable degrees meriting international recognition. Within this context, we analyzed an extensive high-skilled mobility database comprising roughly 382,000 individuals from 5 broad profession groups (Medical, Education, Technical, Science & Engineering, and Business & Legal) over the period 1997-2014, using the 13-country expansion of the European Union (EU) to provide insight into labor market integration. We compare the periods before and after the 2004 enlargement, showing the emergence of a new East-West migration channel between the 13 mostly eastern EU entrants (E) and the rest of the western European countries (W). Indeed, we observe a net directional loss of human capital from E->W, representing 29% of the total mobility after 2004. Nevertheless, the counter-migration from W->E is 7% of the total mobility over the same period, signaling the emergence of brain circulation within the EU. Our analysis of the country-country mobility networks and the country-profession bipartite networks provides timely quantitative evidence for the convergent integration of the EU, and highlights the central role of the UK and Germany as high-skilled labor hubs.We conclude with two data-driven models to explore the structural dynamics of the mobility networks.First, we operationalize a redistribution model to explore the potential ramifications of Brexit, showing the extent to which a 'hard' Brexit, i.e. complete disintegration from the EU, may benefit the overall homogeneity of the European mobility network. Second, we use a panel regression model to explain empirical high-skilled mobility rates in terms of various economic `push-pull' factors, the results of which show that government expenditure on education, per-capita wealth, geographic proximity, and labor force size are significant attractive features of destination countries.
    -European mobility and the potential consequences of Brexit, The Royal Society, Ruth Milne
    -Cover of April 2017 issue of JRSI

  17. A. M. Petersen
    Quantifying the impact of weak, strong, and super ties in scientific careers (pdf)    (short summary)    (Supporting Information)
    Proceedings of the National Academy of Sciences USA 112, E4671-E4680 (2015). DOI:10.1073/pnas.1501444112 Abstract Scientists are frequently faced with the important decision to start or terminate a creative partnership. This process can be influenced by strategic motivations, as early career researchers are pursuers, whereas senior researchers are typically attractors, of new collaborative opportunities. Focusing on the longitudinal aspects of scientific collaboration, we analyzed 473 collaboration profiles using an ego-centric perspective which accounts for researcher-specific characteristics and provides insight into a range of topics, from career achievement and sustainability to team dynamics and efficiency. From more than 166,000 collaboration records, we quantify the frequency distributions of collaboration duration and tie-strength, showing that collaboration networks are dominated by weak ties characterized by high turnover rates. We use analytic extreme-value thresholds to identify a new class of indispensable `super ties', the strongest of which commonly exhibit >50% publication overlap with the central scientist. The prevalence of super ties suggests that they arise from career strategies based upon cost, risk, and reward sharing and complementary skill matching. We then use a combination of descriptive and panel regression methods to compare the subset of publications coauthored with a super tie to the subset without one, controlling for pertinent features such as career age, prestige, team size, and prior group experience. We find that super ties contribute to above-average productivity and a 17% citation increase per publication, thus identifying these partnerships -- the analog of life partners -- as a major factor in science career development.
    -Dynamic duos in science can reap rewards of academic partnerships, Times Higher Education
    -Lifetime collaborators reap the benefits, Nature
    -Quantifying scientific collaboration, Physics Today
    -Publishing Partners, The Scientist
    -Collaboration and scientific career development, PNAS Highlight
    -Study suggests long term collaborations result in more productive scientific careers, Phys.org
    -Collaboration Fosters More Productive Scientific Careers than Competition, Technology.org
    -What science can tell us about building great teams, Kellogg School of Management, Emily Stone

  18. I. Pavlidis, A. M. Petersen, I. Semendeferi
    Together we stand (pdf)
    Nature Physics 10, 700-702 (2014). DOI:10.1038/nphys3110 Abstract During the past 70 years science has been transforming, from the solitary operation that for centuries it used to be, into an endeavor characterized by ever-increasing team size. The importance of this transformation to our technology-driven society cannot be overestimated. As science undergoes this phenomenal evolution, one might expect that the scientific community and its main host - academia - would develop new norms that better serve a new stage. Moth metamorphosis is an example of a natural process that does exactly this, brilliantly adapting form to function. Alas, social constructs are not as flexible as natural processes. The academic career structure originally conceived to reward self-sufficient singletons, continues to be implemented in a system dominated by teams and characterized by symbiotic relationships. To make matters worse, increasingly specialized education leaves academics ill prepared to cope with this challenge. When, how, and why did this malformation start, where does it lead, and how can it be ameliorated? By addressing these questions we bring to the fore the causal links and future projections of the problem, informing a policy and moral dialogue for its resolution.
    -Team Science Is Tied to Growth in Grants With Multiple Recipients, The Chronicle of Higher Education
    -Researchers say academia can learn from Hollywood, Phys.org

  19. A. M. Petersen, S. Fortunato, R. K. Pan, K. Kaski, O. Penner, A. Rungi, M. Riccaboni, H. E. Stanley, F. Pammolli
    Reputation and Impact in Academic Careers (pdf)    (Supporting Information)
    Proceedings of the National Academy of Sciences USA 111, 15316-15321 (2014). DOI:10.1073/pnas.1323111111 Abstract Reputation is an important social construct in science, which enables informed quality assessments of both publications and careers of scientists in the absence of complete systemic information. However, the relation between reputation and career growth of an individual remains poorly understood, despite recent proliferation of quantitative research evaluation methods. Here we develop an original framework for measuring how a publication's citation rate \Delta c depends on the reputation of its central author i, in addition to its net citation count c. To estimate the strength of the reputation effect, we perform a longitudinal analysis on the careers of 450 highly-cited scientists, using the total citations C_i of each scientist as his/her reputation measure. We find a citation crossover cx which distinguishes the strength of the reputation effect. For publications with c < c_x, the author's reputation is found to dominate the annual citation rate. Hence, a new publication may gain a significant early advantage corresponding to roughly a 66% increase in the citation rate for each tenfold increase in C_i. However, the reputation effect becomes negligible for highly cited publications meaning that for c >= c_x the citation rate measures scientific impact more transparently. In addition we have developed a stochastic reputation model, which is found to reproduce numerous statistical observations for real careers, thus providing insight into the microscopic mechanisms underlying cumulative advantage in science.
    -Recognition: Build a reputation, Nature Jobs
    -Being a big name in science brings benefits, Nature
    -Researchers prefer citing researchers of good reputation, Phys.org
    -Scientists' reputations and citation rates, PNAS Highlight

  20. A. M. Petersen, I. Pavlidis, I. Semendeferi
    A quantitative perspective on ethics in large team science (pdf)
    Science & Engineering Ethics 20, 923-945 (2014). DOI:10.1007/s11948-014-9562-8 Abstract The gradual crowding out of singleton and small team science by large team endeavors is challenging key features of research culture. It is therefore important for the future of scientific practice to reflect upon the scientists' ethical responsibilities within teams. To facilitate this reflection we show labor force trends in the US revealing a skewed growth in academic ranks and increased levels of competition for promotion within the system; we analyze teaming trends across disciplines and national borders demonstrating why it is becoming difficult to distribute credit and to avoid conflicts of interest; and we use more than a century of Nobel prize data to show how science is outgrowing its old institutions of singleton awards. Of particular concern within the large team environment is the weakening of the mentor-mentee relation, which undermines the cultivation of virtue ethics across scientific generations. These trends and emerging organizational complexities call for a universal set of behavioral norms that transcend team heterogeneity and hierarchy. To this end, our expository analysis provides a survey of ethical issues in team settings to inform science ethics education and science policy.
    - Family values, Philip Ball (Chemisty world, April 17, 2014)

  21. A. M. Petersen, J. Tenenbaum, S. Havlin, H. E. Stanley, M. Perc
    Languages cool as they expand: Allometric scaling and the decreasing need for new words (pdf)
    Scientific Reports 2, 943 (2012). DOI:10.1038/srep00943 Abstract Language is the hallmark of our cumulative culture, by which means we are able to continuously improve on the achievements of previous generations. According to the most recent estimates, the size of the English lexicon has grown by roughly 88% during the 20th century alone. But what is the utility of so many new words? What is the reach of each new word? Since many new words are technical, what is the likelihood of encountering them, and alternatively, what is the use in remembering them? Underlying these questions is the pressure applied by technological change, which is fundamentally altering the ways in which humans communicate, store, and recall information. We test the stability of the large-scale statistical properties of written language over the 209-year period 1800-2008, analyzing the Zipf law, the Heaps' law, and the size-variance relation quantifying langauge growth patterns for all Google 1-gram databases comprising 7 different langauges. We find that the annual growth fluctuations of word use has a decreasing trend as the corpus size increases, indicating a slowdown in linguistic evolution following language expansion. This "cooling pattern" forms the basis of a third statistical regularity, which unlike the Zipf and the Heaps law, is dynamical in nature.
    - Choice Words: Graphing the evolution of language, arts&sciences Fall 2013 Magazine (Annual BU Research Highlight)
    - How big is your language?, The Hindu, (Dec. 20, 2012)
    - Physicists Explore The Rise And Fall Of Words, Inside Science News Service (ISNS)
    - When physicists do linguistics, The Boston Globe / International Herald Tribune (Feb. 10/11, 2013)

  22. A. M. Petersen, M. Riccaboni, H. E. Stanley, F. Pammolli.
    Persistence and Uncertainty in the Academic Career (pdf)
    Proceedings of the National Academy of Sciences USA 109, 5213 - 5218 (2012). DOI:10.1073/pnas.1121429109 Abstract Recent shifts in the business structure of universities and a bottleneck in the supply of tenure track positions are two issues that threaten to change the longstanding patronage system in academia. Understanding how institutional changes within academia may affect the overall potential of science requires a better quantitative understanding of how careers evolve over time. Since knowledge spillovers, cumulative advantage, and collaboration are distinctive features of the academic profession, the employment relationship should be designed to account for these factors. We quantify the impact of these factors in the production n_i(t) of a given scientist i by analyzing the longitudinal career data of 300 scientists and compare our results with 21,156 sports careers comprising a non-academic labor force. The increase in the typical size of scientific collaborations has led to the increasingly difficult task of allocating funding and assigning recognition. We use measures of the scientific collaboration radius, which can change dramatically over the course of a career, to provide insight into the role of collaboration in productio n efficiency. We introduce a model of proportional growth to provide insight into the complex relation between knowledge spillovers, competition, and uncertainty at the individual scale. Our model shows that high competition levels can make careers vulnerable to ``sudden death'' termination relatively early in the career as a result of negative production fluctuations and not necessarily due to lack of individual persistence.
    - Short-term contracts may hinder young scientists, PNAS Highlight

  23. A. M. Petersen, J. Tenenbaum, S. Havlin, H. E. Stanley.
    Statistical Laws Governing Fluctuations in Word Use from Word Birth to Word Death (pdf)
    Scientific Reports 2, 313 (2012). DOI:10.1038/srep00313 Abstract In this aggregate analysis of the growth rates of millions of words we demonstrate significant signatures of competition driven systems in the linguistic arena of English, Spanish and Hebrew. How often a given word is used, relative to other words, can convey information about the word's linguistic utility. Using Google word data for 3 languages over the 209-year period 1800-2008, we found by analyzing word use an anomalous recent change in the birth and death rates of words, which indicates a shift towards increased levels of competition between words as a result of new standardization technology. We demonstrate unexpected analogies between the growth dynamics of word use and the growth dynamics of economic institutions. Our results support the intriguing concept that a language's lexicon is a generic arena for competition which evolves according to selection laws that are related to social, technological, and political trends. Specifically, the aggregate properties of language show pronounced differences during periods of world conflict, e.g. World War II.
    - F1000 Evaluated Article, Faculty of 1000 post-publication peer review
    - The New Science of the Birth and Death of Words, Wall Street Journal (Mar. 17, 2012)
    - Languages Lose Vocab to Science and Spell-Check, InnovationNewsDaily
    - Digital Spell-Checking May Be Killing Off Words, LiveScience / MSNBC / Discovery.com
    - Modern era brings death to words, ScienceNews
    - Study tracks births, deaths of words, United Press International (UPI)
    - Study reveals words' Darwinian struggle for survival, theGuardian
    - La guerra de las palabras, el Espectador (Colombia)
    - Word Extinction, A nice blog summary by Dev Gualtieri (Aug. 11, 2011)

  24. A. M. Petersen, W-S. Jung, J-S. Yang, H. E. Stanley.
    Quantitative and Empirical demonstration of the Matthew Effect in a study of Career Longevity (pdf)
    Proceedings of the National Academy of Sciences USA 108, 18-23 (2011). DOI:10.1073/pnas.1016733108 Abstract In many competitive systems, there are typically only few "big winners." This largely reflects the everyday fact that obtaining future opportunities often depends on an individual's record of achievement since employment opportunities are limited to a finite number of competitors. We solve exactly a longevity model which predicts the distribution of career length P(x) for professions characterized by high selectivity and uncertainty. We confirm the model's prediction for P(x) using extensive empirical data for the careers of both scientists (publishing in high-impact journals such as Nature, Science, etc.) and professional athletes (playing in MLB, NBA, Premier League, and Korean Professional Baseball). This study uncovers a remarkably simple statistical law which describes the frequencies of the extremely short careers of `one-hit wonders' as well as the extremely long careers of the `iron-horses'. Our model highlights the importance of early career development, showing that many careers are stunted by the relative disadvan- tage associated with inexperience.

  25. A. M. Petersen, O. Penner, H. E. Stanley.
    Methods for detrending success metrics to account for inflationary and deflationary factors (pdf)
    Eur. Phys. J. B 79, 67-78 (2011). DOI:10.1140/epjb/e2010-10647-1
    Pre-print title: Detrending career statistics in professional Baseball: accounting for the Steroids Era and beyond Abstract We compare both career and seasonal achievements of 130+ years of baseball players, (e.g., addressing the question of who effectively hit more home runs -- Babe Ruth or Barry Bonds?), using statistical methods to account for time-dependent factors that inflate success measures. We provide non-technical top-50 record tables for career HR, H, RBI, W, K and season HR, H, RBI, K, focussing on the accessible measures found in newspaper box-scores and on the back of baseball cards.
    - Complexity Theory and the National Baseball Hall of Fame, the European Physical Journal News Highlights
    - New Statistical Method Ranks Sports Players From Different Eras, MIT Technology Review
    - Boston University clip, The Daily Free Press
    - A Physics Curveball, arts&sciences Fall 2010 Magazine (Annual BU Research Highlight)
    - Baseball Greats Reranked, BU Today, April 8, 2011

  26. A. M. Petersen, F. Wang, S. Havlin, H. E. Stanley.
    Quantitative law describing market dynamics before and after interest-rate change (pdf)
    Physical Review E 81, 066121 (2010). DOI:10.1103/PhysRevE.81.066121 Abstract We analyze the financial "earthquake" that occurs evey time the U.S. Federal Reserve makes an announcement to change the federal target interest rate, and estimate the magnitude of market `anticipation' and `surprise' using the fundamental relationship between the federal effective `overnight' interest rate and the 6-month Treasury Bill.
    - Bernanke Announcement Leaves Quake Like Aftershocks , Inside Science News Service

  27. A. M. Petersen, W-S. Jung, H. E. Stanley.
    On the distribution of career longevity and the evolution of home run prowess in professional baseball (pdf)
    Europhysics Letters 83, 50010 (2008). DOI:10.1209/0295-5075/83/50010 Abstract How is it that 3% of all fielders finish their career with one at-bat and 3% of all pitchers finish their career with less than one inning pitched; Yet, there are also some careers that span more than 10,000 at-bats and 3,000 innings pitched? Analyzing every Major League Baseball player career over the 80-year period 1920-2000, we find a beautiful statistical law which describes both the extremely short careers of `one-hit wonders' as well as the extremely long careers of the `iron-horses'. Furthermore, analyzing home run rates, we find evidence consistent with performance enhancing drugs during the `Steroids Era' of the 1990's and 2000's.

  28. M. Mobilia, A. Petersen, S. Redner.
    On the role of Zealotry in the Voter Model (pdf)
    J. Stat. Mech. 08, P08029 (2007). DOI:10.1088/1742-5468/2007/08/P08029 Abstract Why is it that in the history of democratic elections (e.g. Presidential elections), complete consensus (polarization) has never been achieved? For example, the largest percentage of voters for U.S. President elect was approximately 61% in Johnson over Goldwater, 1964. We investigate a stochastic opinion model in which consensus is stymied by the presence of zealots, agents who are completely fixed in their opinion, even if all their neighbors are of opposite opinion. Surprisingly, we find that the number and not the density of zealots determines the degree of consensus among the voters in our model.

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