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Communication in the aftermath of the Boston Marathon Bombing David Lazer Ryan Kennedy Drew Margolin August 16, 2013 132 Nightingale Hall Northeastern University Boston, Massachusetts 02115

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Communication in the aftermath of the Boston Marathon Bombing

David Lazer

Ryan Kennedy

Drew Margolin

August 16, 2013

132 Nightingale Hall

Northeastern University

Boston, Massachusetts 02115


                                               Northeastern study examines responses to Boston Marathon bombing

Executive Summary:

Researchers at Northeastern University conducted a survey June 27 to July 5, 2013 to see how people found out about the Boston Marathon bombing, how they attempted to get information about those they feared were physically affected by the bombing, and where they heard incorrect information about the situation. Notable findings include:

• Television is still the dominant means of finding out about the emergency, with about 47% of respondents finding out about the bombings through this medium. Cell phones and electronic media, however, are rapidly increasing in popularity. During the 9/11 attacks only about 5% of respondents reported receiving information from cell phones, computers or tablets. Nearly 30% reported using these media after the Boston Marathon bombing. Learning of the event via cell phone went from about 2% after 9/11 to almost 10% after the Marathon bombing.

• Respondents closer to the emergency event were more likely to find out from their cell phones. Younger people were also much more likely to find out information from their cell phones. Of those who learned of the situation by cell phone, 52% were under age 40 and 94% were under 60. Interestingly, African Americans are less affected by this trend than other groups. They were almost 12% more likely to learn about the events through TV than other groups, and were 14% less likely than other groups to learn from a cell phone, computer, or tablet.

• Cell phones are the dominant means for gathering information about people about whom respondents were concerned might have been physically affected. Those further from the incident were more likely to use e-mail or Facebook, while people within Boston tended to prefer texting over calling.

• Television was also the primary means by which people heard false information (e.g. the JFK Library had been bombed) in the wake of the bombing. Those closer to the bombing were more likely to hear false information from face-to-face contact, but they were also the most likely to subsequently hear that the rumor was false. For example, 48% of residents of Massachusetts heard that there was no bombing of the JFK Library, while only 24% of people from other states heard that this rumor was false.

• People in Massachusetts responded much more emotionally than residents of other states. For example, 60% of Massachusetts residents reported being “very angry” and 51% reported being “very frightened” or “somewhat frightened,” versus 45% and 28% for the rest of the country.

A second report will be issued in the Fall based on data collected from smartphones. Volunteers with Android phones are still being sought to take survey on their phone usage during the week of the Marathon bombing.

People can volunteer for the study at



On April 15, two bombs exploded near the finish line of the Boston Marathon. This report addresses a number of questions that were raised about the flow of information related to the attack. From which sources do people learn about terrorist attacks? Who do they call when an attack occurs? How do they get information about friends and loved ones physically affected by the attack? And how do rumors spread in the wake of tragedy?

As part of our ongoing research on the way that people use communication technology and social networks to respond to disasters, researchers at Northeastern University have collected several datasets related to the bombings at the Boston Marathon. Highlighted below are analyses from a national and local survey in which people were asked to recall their use of communication technology in response to the bombings. The survey was conducted by YouGov, from June 27 to July 5, 2013, and collected responses from 1,000 people with 500 of those respondents from Massachusetts, and 500 from a representative national sample. The following pages summarize the findings of an initial analysis from the data.



                                               Television is Main Means of Learning of Bombings, But Cell Phones Increasingly Important

The bombing was an extraordinary and unexpected event, and in the aftermath, information regarding the event ricocheted through the informational networks of society. How people found out about the event offers a snapshot of how urgent information reaches individuals when they are not looking for that information.

How did people learn of the bombings? Television is the dominant means, with roughly half of people surveyed saying they heard it first from TV (above), or via a computer. But the closer people were to Boston, the more likely they learned via a cell phone call or text, or told in person. This is presumably due to other people reaching out to contact them by phone.



The growing importance of the cell phone can be seen in two ways. First, compared with the terrorist attacks of 9/11, many more people learned of the Boston Marathon bombings via cell phone (above). Of course, we must be careful in comparing 9/11 and the Boston Marathon bombings, since the 9/11 attacks occurred early in the morning, while the Boston Marathon bombing occurred in the afternoon. Second, there is more evidence of this trend when we consider who is learning via cell phone. People over 60 learned about the Boston Marathon in roughly the typical way that people learned about 9/11 (mostly television, little cell phone). But people under 40 show a much stronger tendency to learn via cell phone, with the cell phone being the second highest ranking medium (after television), and somewhat close to it in percentage (40% television; 23% cell phone) (below). (Note that a multivariate analysis will be necessary to separate this from other relationships identified below, such as employment status.)




                                               African Americans were more likely to learn about the bombing from television

Despite these trends, African Americans showed a substantially higher likelihood of learning of the bombings from television, with fewer learning from cell phones or computers. Individuals without full time employment were more likely to hear about the bombings from TV Employment also makes a difference in how people heard about the bombings. Overall, those without full-time employment were much more likely to hear about the bombings from TV. This was less the case in Massachusetts, where there was also a stark difference in people learning about the bombings face-to-face, with those who had full-time employment being much more likely to hear the news in person.




                                               People Turn to Personal Networks for Information

While the period immediately after the bombing reflects how urgent information finds individuals, the period after the bombing reflects how people actively searched for information in a crisis situation. One might assume that individuals closer to Boston were particularly motivated to get information; and it is useful to distinguish how people found information regarding people about whom they were concerned as compared to ongoing events in the response to the emergency.

Individuals were asked if they sought information about specific individuals about whom they were concerned. Among those answered yes to this question, people turn heavily to phone calls and texts to seek more detailed information about the people they care about. Interestingly, people who were farther from the disaster (Outside Massachusetts) were much less likely to use phones, however, and more likely to turn to Facebook or e-mail. This is likely due to the fact that the person they were concerned with was a weak tie or acquaintance, rather than a strong tie or close friend.


                                               How Do Personal Networks Compare to Traditional Media in Information Quality?

The period immediately after the emergency presented a whirlwind of information and misinformation. Here we identify patterns of spread of two particular false reports that were widely spread by both traditional and social media: that cell phone service in Boston was cut immediately after the bombing, and the JFK library had been bombed.

People nearer to the disaster were more likely to be exposed to false information (above). This could be because they were more actively seeking any information, or because individuals and media in their networks were more likely to share information quickly, before it could be confirmed.

This “over-sharing” hypothesis is somewhat supported by the fact that people nearer to the disaster were more likely to learn a false fact from another person (e.g. face-to-face, via Facebook, or via a call or text), rather than from mainstream media, when compared with those distant from the disaster (below).



While conversations appear to be a culprit in spreading false information to people near a disaster, they also appear to be more likely to transmit clarifications and corrections. Most people in Boston heard that the rumor was false, while people far from the disaster were very unlikely to find this out. In particular, among those who had heard the refutation of the rumor, Bostonians were less likely to hear it from traditional broadcast media (television and radio) and more likely to hear it via the Internet and directly from other individuals, presumably reflecting a higher level of attention and activation of social networks.



How Did the Massachusetts Holiday Affect Who Respondents Were With During Bombing? The fact that the bombing took place on a holiday in Massachusetts made it much more likely that respondents within Massachusetts were with their children or friends when the bombing took place. They were also more likely to be with other family members, but the differences are less substantial between those in Massachusetts and respondents in other areas of the US.



People within Massachusetts were also much more likely to contact someone within the first hour after the bombing than were people outside Massachusetts, again reflecting the much higher activation of social networks closer to the emergency.


                                               People in Massachusetts Had Much Stronger Emotional Reaction to Bombings



Perhaps not surprisingly, those respondents who live in Massachusetts had a much stronger emotional reaction to the bombings. Residents of Massachusetts reported much higher levels of anger, sadness, and fear than the rest of the United States. The largest gaps, however, were in the level of fear. Those within Massachusetts felt a much stronger sense of danger than residents of other states.


                                                Notes re authors David Lazer is Professor of Political Science and Computer Science at Northeastern University, Director of the Program on Networked Governance at Harvard, and affiliate of the Institute for Quantitative Social Science at Harvard. Ryan Kennedy is a visiting faculty at Northeastern University, Assistant Professor at the University of Houston. Drew Margolin is an Assistant Professor of Communication at Cornell University and former postdoctoral fellow at Northeastern University and affiliate of the Institute for Quantitative Social Science at Harvard. Acknowledgements This report has been written by the LazerLab at Northeastern University. Contributors include David Lazer, Ryan Kennedy, and Drew Margolin. This report has benefited from presentation of earlier results at the Taubman Center at the Harvard Kennedy School, as well as from feedback from Laszlo Barabasi. Support from the Defense Threat Reduction Agency, the National Science Foundation, and Northeastern University are gratefully acknowledged. The opinions expressed herein are the authors alone.


                                               Technical appendix The survey was conducted by YouGov from June 27 to July 5, 2013. YouGov interviewed 1,104 respondents who were then matched down to a sample of 1000 produce the final dataset. Subjects were recruited through web advertising campaigns, permission-based e-mail campaigns, partner sponsored solicitations, telephone-to-Web recruitment, and mail-to-web recruitment. The respondents were matched to a sampling frame on gender, age, race, education, party identification, ideology, and political interest. The frame was constructed by stratified sampling from the full 2010 ACS sample with selection within strata by weighted sampling with replacements (using the person weights on the public use file). Data on voter registration status and turnout were matched to this frame using the November 2008 Current Population Survey. Data on interest in politics and party identification were then matched to this frame from the 2007 Pew Religious Life survey.

The matched cases were weighted to the sampling frame using propensity scores. The matched cases and the frame were combined and a logistic regression was estimated for inclusion in the frame. The propensity score function included years of education, gender, race/ethnicity, news interest and ideology. The propensity scores were grouped into deciles of the estimated propensity score in the frame and post-stratified according to these deciles. Weights larger than 7 were trimmed and the final weights normalized to equal the sample size.


                                                Data Appendix: Raw Data for Charts Figure  1:  How  Respondent  Learned  About  Bombing  by  Location  

  Boston   Near  Boston  

Outside  Boston  

Outside  Massachusetts  

Told  in  person   8   34   39   38     0.154   0.182   0.159   0.077  radio   3   17   26   46     0.058   0.091   0.106   0.093  tv   25   77   114   246     0.481   0.412   0.463   0.497  landline  call   0   4   5   6     0.000   0.021   0.020   0.012  cell  phone   8   26   27   35     0.154   0.139   0.110   0.071  computer  or  tablet   8   29   35   124     0.154   0.155   0.142   0.251    

Figure  2:  How  Respondent  Learned  About  9/11  by  Location  

  Boston   Near  Boston  

Outside  Boston  

Outside  Massachusetts  

radio   6   31   22   68     0.118   0.168   0.093   0.140  tv   24   76   102   227     0.471   0.413   0.430   0.469  social  media   0   0   2   3     0.000   0.000   0.008   0.006  internet  news   2   6   5   8     0.039   0.033   0.021   0.017  cell  phone   1   5   2   9     0.020   0.027   0.008   0.019  home  phone   1   11   20   38     0.020   0.060   0.084   0.079  e-­‐mail   0   1   0   0     0.000   0.005   0.000   0.000  told  in  person   16   51   77   125     0.314   0.277   0.325   0.258  


                                               office  phone   1   3   7   6     0.020   0.016   0.030   0.012    

Figure  3:  How  Respondent  Learned  About  Boston  Marathon  Bombing  by  Age  

  Elder   Middle  Age  


Told  in  person   14   51   58     0.053   0.127   0.176  radio   18   55   19     0.068   0.136   0.058  tv   178   171   119     0.674   0.424   0.362  Call  on  landline   1   10   7     0.004   0.025   0.021  cell  phone   6   41   51     0.023   0.102   0.155  computer  or  tablet   47   75   75     0.178   0.186   0.228    


Figure  4:  How  Respondent  Learned  About  Boston  Marathon  Bombing  by  Race  

  white   black   Hispanic  told  in  person   102   3   8     0.128   0.041   0.119  radio   78   4   4     0.098   0.054   0.060  tv   361   51   32     0.454   0.689   0.478  call  on  landline   11   3   3     0.014   0.041   0.045  cell  phone   77   4   7     0.097   0.054   0.104  computer  or  tablet   166   9   13     0.209   0.122   0.194    






Figure  5:  How  Respondent  Learned  About  Boston  Marathon  Bombing  by  Location  and  Type  of  Employment  

  In  Massachusetts   Outside  Massachusetts  

  full-­‐time  job  

not  full-­‐time  


not  full-­‐time  

told  in  person   46   35   21   17     0.118   0.059   0.054   0.029  radio   24   22   25   21     0.061   0.037   0.064   0.036  tv   67   149   62   184     0.171   0.253   0.159   0.312  call  on  landline   6   3   2   4     0.015   0.005   0.005   0.007  cell  phone   29   32   18   17     0.074   0.054   0.046   0.029  computer  or  tablet   32   40   59   65     0.082   0.068   0.151   0.110    

Figure  6:  How  Respondent  Sought  Information  About  Person  For  Whom  They  Were  Concerned  

  Boston   Near  Boston   Outside  Boston   Outside  Massachusetts  

Did  not  contact  anyone  

0.000   0.013   0.000   0.227  

Talked  in  person   0.143   0.091   0.078   0.114  Called  on  phone   0.429   0.597   0.594   0.364  Sent  a  text   0.536   0.545   0.453   0.205  Sent  an  e-­‐mail   0.178   0.169   0.141   0.205  Posted  to  Facebook  

0.214   0.169   0.203   0.250  

Sent  a  Tweet   0.036   0.039   0.031   0.023  Called  over  VOIP   0.000   0.000   0.016   0.023  Sent  an  IM   0.000   0.013   0.031   0.090  Other   0.036   0.026   0.047   0.045  


                                               Note:  Respondents  were  asked  to  indicate  all  methods  they  used  to  contact  someone  they  were  worried  might  have  been  physically  affected  by  the  bombings,  so  cells  indicate  the  proportion  of  all  people  in  these  regions  who  indicated  that  they  used  these  methods  and  tried  to  find  information.  




Figure  7:  Proportion  of  Respondents  Who  Heard  that  the  JFK  Library  Had  Been  Bombed  or  the  Cell  Service  Had  Been  Cut  in  Boston  by  Location  

  Cell  Service  Cut   JFK  Library  Bombed  

Boston   0.804   0.824  Near  Boston   0.710   0.747  Outside  Boston   0.631   0.614  Outside  Massachusetts   0.389   0.316    

Figure  8:  Where  Respondents  Heard  JFK  Library  Had  Been  Bombed  by  Location  

  Boston   Near  Boston   Outside  Boston   Outside  Massachusetts  

Radio   0.076   0.103   0.141   0.093  Radio  website   0.013   0.021   0.012   0.018  TV   0.367   0.420   0.485   0.427  TV  website   0.076   0.041   0.056   0.053  Print  newspaper   0.000   0.024   0.024   0.026  Online  newspaper   0.051   0.049   0.044   0.044  Internet  news   0.139   0.148   0.100   0.198  Facebook   0.101   0.041   0.056   0.040  Twitter   0.051   0.015   0.016   0.040  Reddit   0.013   0.008   0.000   0.022  Tumblr   0.000   0.000   0.000   0.000  Person  through  device  

0.051   0.049   0.032   0.004  

Person  face-­‐to-­‐face   0.063   0.045   0.020   0.026  Other   0.000   0.004   0.012   0.009    

Figure  9:  Respondents  Who  Heard  Rumor  About  JFK  Library  Bombing  Was  FALSE  

  Heard  False   Did  Not  Hear  False  


                                               Boston   28  

0.549  23  

0.451  Near  Boston   97  

0.522  89  

0.478  Outside  Boston   111  

0.461  130  0.539  

Outside  Massachusetts   122  0.253  

361  0.747  



Figure  10:  Where  Respondent  Heard  JFK  Library  Had  NOT  Been  Bombed  by  Location  

  Boston   Near  Boston   Outside  Boston   Outside  Massachusetts  

Radio   0.108   0.147   0.132   0.106  Radio  website   0.000   0.000   0.018   0.017  TV   0.432   0.489   0.560   0.469  TV  website   0.081   0.021   0.036   0.050  Print  newspaper   0.000   0.028   0.024   0.011  Online  newspaper   0.081   0.077   0.048   0.056  Internet  news   0.135   0.126   0.072   0.184  Facebook   0.054   0.042   0.060   0.033  Twitter   0.000   0.028   0.006   0.017  Reddit   0.000   0.000   0.000   0.011  Tumblr   0.000   0.000   0.000   0.011  Person  through  device  

0.054   0.021   0.012   0.011  

Person  face-­‐to-­‐face   0.054   0.021   0.018   0.017  Other   0.000   0.000   0.012   0.006    

Figure  11:  Who  was  Respondent  With  When  Heard  About  the  Bombing  

  In  Massachusetts   Outside  Massachusetts  

Husband   0.103   0.092  Wife   0.113   0.092  Boyfriend   0.047   0.024  Girlfriend   0.027   0.016  Mother   0.060   0.054  Father   0.033   0.020  Children   0.140   0.052  Other  family   0.060   0.036  


                                               Friends   0.118   0.082  Others   0.130   0.120  No  one   0.361   0.479    

Figure  12:  Did  Respondent  Try  to  Contact  Someone  in  First  Hour  After  Bombing  by  Location  

  In  Massachusetts   Outside  Massachusetts  Tried  to  contact  someone   347  

0.715  250  0.503  

Did  not  try  to  contact  someone   138  0.285  

247  0.497  


Figure  13:  Level  of  Anger  Expressed  by  Respondent  by  Location  

  In  Massachusetts   Outside  Massachusetts  Very  angry   293  

0.605  225  0.454  

Somewhat  angry   111  0.229  

140  0.282  

Neither  angry  nor  not  angry   63  0.130  

97  0.196  

Not  very  angry   9  0.019  

12  0.024  

Not  at  all  angry   8  0.017  

22  0.044  


Figure  14:  Level  of  Sadness  Expressed  by  Respondent  by  Location  

  In  Massachusetts   Outside  Massachusetts  Very  sad   351  

0.725  292  0.590  

Somewhat  sad   97  0.200  

134  0.271  

Neither  sad  nor  not  sad   27  0.056  

43  0.087  

Not  very  sad   3  0.006  

11  0.022  

Not  at  all  sad   6  0.012  

15  0.030  



                                               Figure  15:  Level  of  Fright  Expressed  by  Respondent  by  Location  

  In  Massachusetts   Outside  Massachusetts  Very  frightened   103  

0.269  44  

0.089  Somewhat  frightened   148  

0.306  94  

0.189  Neither  frightened  nor  not  frightened  

120  0.247  

139  0.281  

Not  very  frightened   45  0.093  

88  0.178  

Not  at  all  frightened   68  0.140  

130  0.263