reputation and impact in academic careers
TRANSCRIPT
Acknowledgements
Pietro Parolo
Marija Mitrović Arnab Cha7erjee Francesco Beca7ini
Raj K. Pan
Kimmo Kaski
Orion Penner Alex Petersen
Fabio Pammolli
Massimo Riccaboni Gene Stanley
The role of reputation …
A. M. Petersen, S. F., R. K. Pan, K. Kaski, O. Penner, A. Rungi, M. Riccaboni, H. E. Stanley, F. Pammolli,
Proc. Natl. Acad. Sci. USA 111, 15316-‐‑15321 (2014)
Question: what is the role of author’s reputation on citation dynamics?
Reputation variable
A. M. Petersen, S. F., R. K. Pan, K. Kaski, O. Penner, A. Rungi, M. Riccaboni, H. E. Stanley, F. Pammolli,
Proc. Natl. Acad. Sci. USA 111, 15316-‐‑15321 (2014)
Measure of reputation of author i at time t: cumulative number of citation Ci(t), from the beginning of i’s career until year t
Issues: 1. H-‐‑index? 2. It does not account for quality: high values of Ci(t) can be
achieved with many low-‐‑impact papers 3. Effect of reputation of coauthors? 4. It can only grow in time, while reputation may also
decrease (misconduct, fraud)
Ci(t) ⇠ hi(t)1+�i
Other variables
A. M. Petersen, S. F., R. K. Pan, K. Kaski, O. Penner, A. Rungi, M. Riccaboni, H. E. Stanley, F. Pammolli,
Proc. Natl. Acad. Sci. USA 111, 15316-‐‑15321 (2014)
t = Career age, number of years since first publication
⌧ = Paper age, number of years since first citation
Ni(t) = Total number of papers published by i until year t
⌧ c1/2 = Half-life of paper c
ci,p(t) = Citations of paper p and author i until time t
�ci,p(t) = Citations received by paper p of author i in year t
Our data A. Prolific authors of Physical Review Le0ers (PRL) (1958-‐‑2008) B. Highly productive physicists C. Young assistant professors from US Top 50 physics and
astronomy departments D. Prolific authors of Cell E. Prolific authors of Annals of Mathematics
1. 300 physicists 2. 100 biologists 3. 50 mathematicians
Summary
A. M. Petersen, S. F., R. K. Pan, K. Kaski, O. Penner, A. Rungi, M. Riccaboni, H. E. Stanley, F. Pammolli,
Proc. Natl. Acad. Sci. USA 111, 15316-‐‑15321 (2014)
Reputation and citation dynamics: cumulative
hN 0(t)i ⇠ t↵̄, hC 0(t)i ⇠ t⇣̄
↵̄ & 1, ⇣̄ > ↵̄
Superlinear algebraic growth!
Reputation and citation dynamics: individual careers
c(r) / r��(N + 1� r)�Rank-‐‑citation profile: discrete generalized β-‐‑distribution:
Citation life-‐‑cycle
• Citation peak before publication age τ ≈ 5 years • Slower decay for highly cited papers • Long half-‐‑life for papers in math
Citation life-‐‑cycle: half-‐‑life versus number of citations
⌦̄
⌧1/2 ⇠ c⌦̄p
ranges from 0.3 for Biology to 1 for Mathematics (uniformly distributed impact across time)
The reputation model �ci,p(t+ 1) vs cp(t) ?
Preferential a7achment?
For cp(t) lower than a threshold cx the number of cites exceeds that predicted by preferential a7achment: why?
The reputation model
�ci,p(t+ 1) ⌘ ⌘ ⇥⇧p(t)⇥A⇢(⌧)⇥Ri(t) =
= ⌘ [cp(t)]⇡exp(�⌧p/⌧̄) [Ci(t)]
⇢
noise preferential a7achment
life cycle reputation
Regression model
⇢(c < cx
) > ⇢(c � cx
), ⇡(c < cx
) < ⇡(c � cx
)Main result:
⇢(c � cx
) ⇡ 0
The reputation model
Example (aggregated dataset A/B)
⇢(c < cx
= 40) ⇡ 0.2, ⇢(c � cx
= 40) ⇡ 0
⇡(c < cx
= 40) ⇡ 0.4, ⇡(c � cx
= 40) ⇡ 1
For two scientists such that C1(t)=10 C2(t):
�c1(t)/�c2(t) = 10⇢ ⇡ 1.66 (c < cx
= 40)
66 % increase for each 10-‐‑fold increase in Ci(t) !
Citations are initially boosted by author reputation up to a tipping point cx above which the citation rate is sustained mostly by publication reputation
The Nobel Prize Delay
F. Beca7ini, A. Cha7erjee, S. F, M. Mitrović, R. K. Pan, P. De l l a B r i o7a Pa ro lo , Na tu r e 5 08 , 1 86 ( 2 014 ) h7p://scitation.aip.org/content/aip/magazine/physicstoday/news/10.1063/PT.5.2012
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DataAverageModel
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Chemistry
Year of nobel award19
0019
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5019
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Physiology or Medicine
The Nobel Prize Delay
F. Beca7ini, A. Cha7erjee, S. F, M. Mitrović, R. K. Pan, P. De l l a B r i o7a Pa ro lo , Na tu r e 5 08 , 1 86 ( 2 014 ) h7p://scitation.aip.org/content/aip/magazine/physicstoday/news/10.1063/PT.5.2012
The Nobel Prize Delay
F. Beca7ini, A. Cha7erjee, S. F, M. Mitrović, R. K. Pan, P. De l l a B r i o7a Pa ro lo , Na tu r e 5 08 , 1 86 ( 2 014 ) h7p://scitation.aip.org/content/aip/magazine/physicstoday/news/10.1063/PT.5.2012
Outlook • Author reputation drives the initial phase of the citation dynamics of papers
• After a tipping point, citation accumulation is driven by the paper’s own reputation
• Tip: look for quality! • The lag between discovery and the Nobel prize is growing rapidly
• Extinction of worthy winners? • Decay of (fundamental) science?
Organizing commi7ee: S. Fortunato (Aalto), A. Gionis (Aalto), H. Hämmäinen (Aalto), K. Kaski (Aalto), W. Quahrociocchi (IMT), J. Saramäki (Aalto), J. Valimäki (Aalto)
Lada Adamic Facebook
Sinan Aral MIT
László Barabási Northeastern U.
Nicholas Christakis Yale
Robin Dunbar Oxford
Andreas Flache Gröningen
Dirk Helbing ETH Zürich
Ma7hew Jackson Stanford
Jure Leskovec Stanford
Alex Pentland MIT
Alex Vespignani Northeastern U.
Duncan Wa7s Microsoft
David Lazer Northeastern U.
Michael Macy Cornell