the fox news e ect:media bias and voting s. dellavigna and e. … · 2014. 5. 13. · beliefs and...

Introduction The Experiment Empirical Results Conclusions

The Fox News E�ect:Media Bias and VotingS. DellaVigna and E. Kaplan (2007)

Anna Airoldi Igor CerasaIGIER Visiting Students Presentation

March 21st, 2014


Research Questions

Does the media have an impact of voting behavior?

Can biased information alter individuals' beliefs?

Are individuals able to �lter out information bias that isrepeated over time?


Answers

Rational Expectations Theories

Voters �lter out bias in reporting without being persuaded onaverage (Bray and Kreps, 1987)

Behavioral Theories

Voters are subject to media persuasion (De Marzo, Vayanos andZwiebel, 2003)


Previous studies

Field Experiments (Green and Gerber, 2004)

Households are randomly selected and assigned to right-wingor left-wing newspapers

The e�ect is evaluated in a post-election survey

Increase in the shares of Democratic voters

Lab Experiments (Ansolabehere and Iyengar, 1995)

Experimental subjects are exposed to thirty-second politicaladvertisements supporting a candidate

Beliefs and voting intentions at the end of the experiment

Positive e�ect on the stated voting share


Previous studies (cont.)

Surveys (Kull, Ramsay and Lewis (2003)

Use of surveys to assess the impact of the media

Fox News watchers are more likely to believe that weapons ofmass destruction were found in Iraq in 2003 (33% v. 22%)


Consequences

Di�erent explanations allows for di�erent outcomes

Deregulation of media markets may have a large impact onpolitical outcomes

Answers are a matter of empirical results

Natural Experiment

Impact of the introduction of Fox News Channel on Republicanvote share in 1996 and 2000


The Fox News Channel

"Fox News" was introduced in October 1996

24-hours cable news channel

News broadcast had only a small share

Signi�cantly to the right of all the other mainstream televisionnetworks (Groseclose and Milyo, 2005)

Strong e�ect on the available political information


The Cable Industry

Local natural monopoly due to the �xed cost of laying cables

Only 10 % of cities has more than 1 companies

Technological costraint on the number of channels


The Cable Industry (cont.)

By the year 2000, Fox News was present in 20% of the sampletowns accounting for 34% of the population

Fox News also distributed short news segments to local TVStations a�liated to Fox Broadcasting


Proportion of town with Fox News in each county

RED = 0BLUE = 1


The Data

Local cable companies => Paper copy of the �Television andCable Factbook�, 2001 edition. No info about 1996.

Election Data => Election Division of the Secretary of Statefor each state + Federal Election Project (year 2000) +ROAD Project (year 1988) + Atlas Election Data (year 2004).

Census Data => For the 28 US states collect demographicsfrom the 2000 and the 1990 census at the level of �Place�.


The Data (cont.)

SAMPLE = 28 US states, the ones for which aggregation at thetown level is possible.

1 Match cable, election and Census data by the State, countyand town name

2 Drop towns with multiple cable systems (some with FN somewithout), not o�ering CNN or with likely voting data problems

=> Final sample of 9256 towns with comparable Fox Newsavailability and lower Republican vote share relative to the initialsample.


Selection

Need to investigate the nature of selection and estimate whichtown-level variables predict the availability of Fox News

If Republican areas were becoming more Republican between1996-2000 than the Fox News E�ect may just be capturing politicaltrends.


Linear Probability Model

dFOXk,2000 = α+ βvR,Pres

k,1996 + βT tPresk,1996 + Γ2000Xk,2000+

+Γ00−90Xk,00−90 + ΓCCk,2000 + εk

Where:

dFOXk,2000 is equal to 1 if all cable systems in town k include FoxNews and to 0 if no cable system includes Fox News;

vR,Presk,1996 is the two-party Republican vote share;

tPresk,1996is the voter turnout, ie the log of votes cast as share ofpopulation;

Γ are the coe�cients of controls for census and features of thecable system


Once we control for geographic heterogeneity and size of thecable system, availability of Fox News is uncorrelated withboth political outcome and demographic characteristics;

Conditional on cable market size and within country/districts,assignment to towns within an area is RANDOM!


A Natural Experiment

Random assignment of a treatment (FOX NEWS) to apopulation (The American population) thanks to idiosyncraticdi�erences in access due to decentralization of cable industry;

Can be used to study the e�ects on presidential elections,voter turnout, persuasion rates;

Since Fox News is signi�cantly to the right of all othermainstream television networks, signi�cant e�ect on theavailable political information in that cable market.


Presidential Elections - Regression Framework

Evaluate the change in Republican voting share from 1996 and2000 elections

νR,Presk,2000 − νR,pres

k,1996

Compare towns that had Fox News in 2000

dFOXk,2000 = 1

With respect to towns which did not

dFOXk,2000 = 0


Presidential Elections - Regression Framework (cont.)

Baseline speci�cation

νR,Presk,2000 − νR,pres

k,1996 = α+ βFdFOXk,2000 + Γ2000Xk,2000+

+Γ00−90Xk,00−90 + ΓCCk,2000 + εk

Control variables refer to town-level demographics in absolutevalues (Xk,2000), changes (Xk,00−90) together with cablevariables (Ck,2000)


Presidential Elections - Results


Robustness


Interactions


Placebo Speci�cations


Voter Turnout

Two possible explanations for the impact of Fox News on theRepublican vote share

1 Fox News entry convinced Democratic voters to voteRepublican

2 Fox News attracted new Republican voters


Voter Turnout - Baseline Regression

We estimate the following equation

tPresk,2000−tPres

k,1996 = α+βFdFOXk,2000+γ[log(Popk,2000)−log(Popk,1996)]+

+Γ2000Xk,2000 + Γ00−90Xk,00−90 + ΓCCk,2000 + εk

Where

tPresk,t = log(V TOT,Pres

k,t )

Popk,t refers to the voting-age town population in year t


Voter Turnout - Results


Senate Elections

Is the Fox News e�ect candidate-speci�c or a general

ideological shift?

We test the hypotheses using data from Senate Elections

1 Senate races that failed to get national coverage (72 mentionsin total)

2 The Clinton-Lazio race in New York State (99 mentions)


Senate Elections - Regression Framework

We estimate the following equation

νR,Senk,2000 = α+ αP ν

R,Presk,1996 + βFd

FOXk,2000 + φFd

FOXk,2000 · dNY +

+Γ2000Xk,2000 + Γ00−90Xk,00−90 + ΓCCk,2000 + εk

Where βF indicates the e�ect of Fox News on Senate races otherthan New York and φF indicates the di�erential e�ect for thefeatured New York race


Senate - Results


Persuasion Rate

PERSUASION RATE = try to evaluate the magnitude of the FoxNews E�ect by estimating the share of audience that was convincedby Fox News

To do so, compare treatment town T, where Fox News is available,with control towns C, where Fox News is not available via cable.


Persuasion Rate - The Model

vj =r + (1 − r)ejf

r + d+ (1 − r − d)ejf

Hypothesis:

1 Since towns have similar political outcomes in the pre-FoxNews period conditional on controls, we assume that d and rare the same in T and C

2 Exposure ej in town j to Fox News is independent of politicala�liation => PROBLEMATIC


Persuasion Rate - The Model (cont.)

With some calculations, we get that vT − vC = (eT−eC)fdtCtT

The implied persuasion rate is

f =vT − vC

(eT − eC)(1 − r)

(1 − r)tCtTd

The �rst term is the in�uence rate for treated population, thatis the shift in republican vote share due to the availability ofFox News via cable over the share of population at risk oftreatment.

Second term: di�erential convincing e�ect of Fox News on aDemocrat and a non-voter. Only when a democrat shifts thedemocrats lose a vote. The larger the ratio of non-Republicansto Democrats, the bigger the convincing impact for a givenvote share change.


Estimating Audience

Scarborough research = representative panel of households tocollect demographic variables and two audience measures for eachTV channel surveyed.

Recall = share of respondents who answer yes to the questionon whether they watched a given channel in the past sevendays

Diary = share of respondents who watched a channel for atleast one full half-an-hour block according to a seven-day diaryof TV watching.

SAMPLE: 105,201 respondents from August 2000- March 2001.Using only the subsample of respondents for wich we observe azipcode of residence that can be matched with cable data onavailability of Fox news and aggregating it at town level, get asample of 528 towns.


Estimating Audience (cont.)

eT − eC is the di�erential exposure

eFOXk =

α+ βFdFOXk,2000 + Γ2000Xk,2000 + +Γ00−90Xk,00−90 + ΓCCk,2000 + εk

Where:

eFOXk = fraction of town k residents in the Fox New audience;

dFOXk,2000= availability of Fox News in town k;

βF = di�erential Fox News diary audience due to Fox News'availability via cable in town k.


Estimating Persuasion Rates

Using the expression: f = vT−vC(eT−eC)(1−r)

(1−r)tCtTd we calculate the

persuasion rate, where:

eT �eC is the coe�cient βF of the previous regression;

tC ,tT ,r and d are evaluated using sample averages of the 2000elections, weighted by total votes cast in 2000.

Recall Multiply βF by a conversion rate that is the ratio ofthe CNN recall audience to the CNN diary audience.Estimates for di�erential exposure are 12% and 8%with district and county �xed e�ects. The persuasionrate is 3.39% with congressional district �xed e�ects,8.27% with county �xed e�ects.

Diary The persuasion rate with congressional district �xede�ect is 11.62% and 28.29% with county �xed e�ects.


Explanations

Estimates imply that Fox News convinced a signi�cant portion ofits audience to vote Republican. There are three explanations forthis �nding:

Endogeneity bias = �ndings might be spurios, induced byentry of Fox News in towns that were independently becomingmore conservative. This explanation is not consistent with thefact that entry of Fox News does not predict political votingtrends between 1992 and 1996, but only the ones between1996 and 2000.

Rational learning = if voters are uncertain about the bias ofFox News, exposure will have a temporary e�ect on beliefs andvoting. However, by 2000 the conservative slant of Fox Newsshould have been clear. Moreover, the e�ect seems to bepersistent over time.


Explanations (cont.)

Nonrational Persuasion = viewers do not discount media biasstrongly enough and therefore are subject to nonrationalpersuasion upon exposure => permanent alteration of votingbehaviour. This is associated with a general ideological shifttowards the right.


Main Findings

Fox News had a signi�cant impact on the 2000 elections:according to estimates, it increased Republican vote share inpresidential election by 0.4-0.7%. It was therefore decisive inthe close presidential election, which was decided by around500 votes in Florida;

Fox News impact extends to general political beliefs and isstronger where the population "at risk" is larger;

Fox News increased turnout to the polls;

Fox News conviced between 3 and 28% of its non-Republicanviewers to vote Republican;

=> Media can have a sizeable political impact


Final Observations

The assumption that exposure to Fox News is uncorrelatedwith political a�liation is problematic. If Republicansself-selected into watching Fox News the persuasion rate ofnon-Republicans could be biased downwards;

The time persistence of the e�ect is not really well explained inthe paper;

This paper presents interesting evidence on the voting ofpersuasion-biased agents, which systematically underestimatethe extent of the bias present in the information they receivewhen updating their beliefs.


Four hostile newspapers are more to be feared than a

thousand bayonets (Napoleon Bonaparte)

Whoever controls the media, controls the mind (Jim

Morrison)

the fox news e ect:media bias and voting s. dellavigna and e. … · 2014. 5. 13. · beliefs and...

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