In “Are Voters Sensitive to Terrorism? Direct Evidence from the Israeli Electorate,“ Claude Berrebi and Esteban F. Klor analyze the causal effects of terrorist attacks on the political preferences of the Israeli electorate. In this comment, I discuss Berrebi and Klor's empirical approach - especially their treatment of possible reverse causality between voters' preferences and the occurrence of terrorist attacks - and make suggestions for improvement.terrorism; voter behavior; elections; electoral behavior; political economy; security policy

Hlavac, Marek

English

Research Papers in Economics

1 
 
 
 
 
 
Comment on Claude Berrebi and Esteban F. Klor (2008):  
“Are Voters Sensitive to Terrorism? Direct Evidence from the Israeli Electorate” 
 
 
 
 
 
Marek Hlavac
* 
Georgetown University 
Georgetown Public Policy Institute 
October 2010 
   
                                                           
* Candidate, Master of Public Policy (MPP), Georgetown University, Expected 2011 
  A.B. in Economics, summa cum laude, Princeton University, 2008 2 
 
In  “Are  Voters  Sensitive  to  Terrorism?  Direct  Evidence  from  the  Israeli  Electorate,“ 
Claude Berrebi and Esteban F. Klor analyze the causal effects of terrorist attacks on the political 
preferences of the Israeli electorate. They find that, if a locality suffers a terrorist attack within 
three months of a parliamentary election, support for the right bloc of political parties increases, 
on average, by 1.35 percentage points. This magnitude is politically significant, given that the 
Israeli electorate is narrowly split. In left-leaning localities, interestingly, local terror fatalities 
lead to an increase in the relative support for the right bloc, but terror fatalities outside the 
locality increase support for the left bloc of parties. Terrorist attacks, Berrebi and Klor argue, can 
contribute to the ideological polarization of the electorate: Terrorism, they find, increases support 
for the right bloc in all the right-leaning localities, but decreases support for the right bloc in 
most left-leaning localities. Berrebi and Klor interpret their findings to be, for the most part, 
supportive of the policy voting hypothesis, according to which “parties benefit from the salience 
of issues to which they are generally viewed as attaching highest priority.” (Kiewiet, 1981) 
  Berrebi and Klor’s article contributes to a growing body of research literature on the 
causes and effects of terrorism, defined by Sandler and Enders (2004) as “the pre-meditated use, 
or threat of use, of extra-normal violence to obtain a political objective through intimidation or 
fear directed at a large audience.” Sandlers and Enders (2004) provide a comprehensive review 
of the research literature on the causes and consequences of terrorism. Research on the causes of 
terrorism  has  often  focused  on  the  political  and  socio-economic  determinants  of  terrorism 
(Russell and Miller, 1983; Krueger and Malečková, 2003; Krueger and Laitin, 2008; Piazza, 
2006). Berrebi and Klor’s paper contributes to a burgeoning literature on the effects of terrorism: 
Previous research has studied, inter alia, whether terrorism helps achieve the terrorists’ political 
goals (Pape, 2003), its effects on states’ respect on human rights (Dreher et al., 2010), as well as 3 
 
on specific industries, such as tourism (Drakos and Kutan, 2003).  Berrebi and Klor’s study 
analyzes the effect on terrorism on voter preferences and electoral outcomes – a crucial question, 
given terrorism’s explicit focus on achieving political objectives. In addition, the paper provides 
an important link between the relatively recent literature on the causes and consequences of 
terrorism,  and  a  long  strand  of  academic  literature  on  electoral  behavior  (Bartels,  2008), 
pioneered by Lazarsfeld et al. (1944), Black (1948) and Downs (1957).  
The strengths of Berrebi and Klor’s paper are most apparent in its careful robustness 
tests. In particular, the authors test whether the results hold for alternative ways of including a 
variable for terrorist attacks  (the number of fatalities  suffered, the number of attacks,  and a 
dummy for the occurrence of an attack), as well as for alternative definitions of the right and the 
left political blocs, and for variable time periods before a parliamentary election. 
The most important shortcoming of Berrebi and Klor’s paper lies in their treatment of 
possible reverse causality. The authors correctly point out that a naïve regression model would 
yield biased coefficients, since “terror attacks may influence the electorate’s preferences, but 
terrorism may also be a reaction to those preferences.” Their remedy, however, is unconvincing: 
They  add  to  the  analysis  terror  attacks’  “variation  across  space,”  which  they  show  to  be 
exogenous to the electorate’s political preferences. They, however, estimate a fixed-effect linear 
regression  model  that  does  not  resolve  the  endogeneity  problem  caused  by  terror  attacks’ 
variation over time. Instead, the authors would be well-advised to estimate a two-stage least-
squares  (2SLS)  model,  where  they  explicitly  instrument  for  terrorist  attacks  by  variables 
suggested  by  Berrebi  and  Lakdawalla  (2007):  These  include,  among  others,  the  locality’s 
population, its area (in km
2), the percentage of Jewish residents in the local population, and the 
distance  to  the closest terrorist home base.  Instrumental variables approaches  are a standard 4 
 
econometric method to resolve problems of simultaneity (Wooldridge, 2009), and have been 
used widely in studies of civil and political violence (Miguel et al., 2004; Brunschweller and 
Bulte, 2009). 
Another potential problem arises in Berrebi and Klor’s demonstration that, rather than 
influencing the relative turnout of left- and right-leaning voters, terrorism affects the political 
preferences of the electorate. To test this hypothesis, the authors focus on localities with very 
high turnouts: those, in which the average turnout rate exceeds 85%. In these localities, the 
authors argue, “almost everybody votes” and, therefore, “any influence of terrorist on the relative 
support for the right bloc must be a consequence of voters changing their preferences, and not 
their turnout decisions.” It is, however, conceivable that, even at high turnout rates, some people 
may, in the wake of a terrorist attack, decide to either vote or refrain from going to the polls. 
Although Berrebi and Klor’s conjecture may sound plausible, they need to support their claim by 
further empirical evidence – for instance, from an individual-level panel survey of voters in high-
turnout localities. The authors could obtain this evidence either from existing research on voter 
behavior in Israel, or offer it as a suggestion for further research. 
A final concern involves over-controlling in the specification of the linear regression 
model: In their basic model, the authors include two variables that account for fatalities caused 
by  terrorist  attacks:  TerrorFatalitiesi,t  and  TotalFatalitiest.  TerrorFatalitiesi,t  accounts  for  the 
number  of  fatalities  in  the  examined  locality.  Berrebi  and  Klor  interpret  the  coefficient  on 
TotalFatalitiest (total number of terror fatalities in Israel) as the effect on political attitudes of 
fatalities in other localities. In multiple regression models, coefficients have a “partial effect” 
interpretation:  What  is  the  effect  of  an  additional  local  or  non-local  fatality  on  the  relative 
support  for  the  right  bloc,  holding  everything  else  equal?  The  number  of  local  fatalities, 5 
 
however, cannot increase without a corresponding rise in the total number of terror fatalities in 
Israel.  The  authors  should therefore consider replacing  TotalFatalitiest by  OutsideFatalitiesi,t 
equal to TotalFatalitiest - TerrorFatalitiesi,t. The coefficient on TerrorFatalitiesi,t will then be 
clearly interpretable as the ceteris paribus effect of a local terror fatalities on the political support 
for the right bloc. 
If  Berrebi  and  Klor’s  findings  hold  up,  they  could  have  several  policy  implications: 
Counterterrorism policies that increase terrorism’s salience in the public mind may, they suggest, 
enable  terrorists  to  have  a  greater  effect  on  the  political  process.  By  contrast,  policies  that 
diminish  the  electorate’s  sensitivity  to  terrorism  may  help  lower  the  threat.  In  addition,  the 
author’s work yield important clues about the objectives of terrorist groups: If terrorist attacks 
increase  support  for  the  political  right  (which,  in  Israel,  favors  aggressive  counterterrorism 
measures), such attacks may not help achieve terrorists’ goals (Abrahms, 2006), terror groups 
may  have  multiple  objectives  (Kydd  and  Walter,  2006),  or  there  may  be  a  more  complex 
interplay (Bueno de Mesquita et al., 2006). Finally, policy-makers should be careful in applying 
lessons  from  this  research  to  other  countries.  Additional  research  is  needed  to  test  whether 
Berrebi and Klor’s findings, based on evidence from Israel, extend to different settings. 
All in all, Berrebi and Klor’s is comprehensive in its focus on the support for political 
party blocs, as well as on larger issues such as political polarization; rigorous in its multiple 
robustness  tests;  and  can  yield  important  insights  for  researchers  and  policy-makers.  If  the 
authors successfully address the concerns outlined earlier in this report, they will have made a 
significant contribution to our understanding on the complex interplay between terrorism, voter 
preferences and electoral behavior. 6 
 
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An Economic Perspective on Transnational Terrorism,”

An Economic Theory of Democracy.

Are Voters Sensitive to Terrorism? Direct Evidence from the Israeli Electorate,”

Does Terrorism Threaten Human Rights? Evidence from Panel Data,”

Economic Shocks and Civil Conflict: An Instrumental Variables Approach,”

Education, Poverty, and Terrorism: Is There a Causal Connection?”

How Does Terrorism Risk Vary Across Space and Time? An Analysis Based

Introductory Econometrics: A Modern Approach,

Natural Resources and Violent Conflict: Resource Abundance,

On the Rationale of Group Decision-making,”

Policy-Oriented Voting in Response to

Profile of a Terrorist.”

Rooted in Poverty?: Terrorism, Poor Economic Development,

The People's Choice: How the Voter Makes Up His Mind in a Presidential Campaign.

The Strategic Logic of Suicide

Comment on Claude Berrebi and Esteban F. Klor (2008): “Are voters sensitive to terrorism? Direct evidence from the Israeli electorate”

Comment on Claude Berrebi and Esteban F. Klor (2008): “Are voters sensitive to terrorism? Direct evidence from the Israeli electorate”

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