Public Opinion of Congress a Causal Examination

Download data and study materials from OSF

This experiment was fielded as part of a TESS telephone survey. Data and materials for all the studies included on this survey is available here.

Principal investigators:

Monika L McDermott

Fordham University



David R. Jones

City University of New York, Baruch College



Sample size: 1460

Field period: 10/06/2004-01/24/2005


The question of how citizens evaluate the performance of their own government is a central issue in the study of democratic politics. Despite this, we have very little hard evidence on what actually causes the public to feel the way it does about government and how it performs its job. Decades of cross-sectional, non-experimental studies have led us to many theories of what determines public approval or disapproval – and findings on what correlates with it – but without experimental attempts to manipulate such opinions, we can never know whether our current theories are in fact causal, or merely correlational. This experiment study is the first one to address this causal puzzle. We set out to test the three primary theories of what causes public approval or disapproval of Congress – government processes, national conditions, and ideological policy judgments. Through experimental manipulation of the information survey respondents receive, we can demonstrate whether any of these factors has a truly causal relationship with public judgments of congressional performance.


(1) That governmental processes – efficiency versus inefficiency – cause public judgments of Congress.
(2) That national forces – the economy – cause public judgments of Congress.
(3) That ideological policy judgments – based on liberal or conservative congressional actions – cause public judgments of Congress

Experimental Manipulations

Efficient government
Inefficient government
Good economy
Bad economy
Liberal policy action
Conservative policy action
As well as a control condition in which respondents received no information.


Opinions of Congress, post-experimental manipulation, for each experimental group relative to the control group

Summary of Results

Only the subjects/respondents receiving the liberal policy information expressed significantly different views of Congress than did the control group. Specifically, both conservative and moderate respondents had more negative views of Congress, having heard the liberal scenario, than did control group members who heard no scenario. This provides strong support for the ideological policy theory of congressional approval.


This experiment provides the first causal test of what contributes to opinions of Congress. While multiple cross-sectional analyses have posited theories – primarily government processes, national conditions, and ideological policy judgments – none has been able to establish causality. The results of this experiment do just that. They demonstrate that when people hear about ideological actions taken by Congress, they react ideologically. Opinions become more negative for those who are ideologically opposed, but more positive for those ideologically similar.
The results provide no support, however, for either national forces or government process effects.





2007. Throwing the Bums Out: Causes and Consequences of Public Judgments of Congress. (data make up Chapter 2).
2005. “Public Approval of Congress: A Causal Examination.” Paper presented at the World Association for Public Opinion Research regional conference, Hong Kong, December.