-obstacles to establishing causality:
-confounding variables – causes: spurious, misguided, and hidden relationships
-research designs: strategies researchers use to test whether x causes y
research design I: experiments
-logic of experimentation:
-definition of experiment:
-the researcher controls values of independent variables
-the researcher also randomly assigns values of indebtedness variables to the
-divide participants into 2 groups
-random assignment: we put each individual into each group randomly.
-if there is Z that are of confounding variables b/w x and y, the Random
Assignment would balance the Z between the two groups.
-different types of experiments:
-i. laboratory experiment
-in a laboratory
-recruited voluntary participants
-ii. Field experiment
-conducted in a real world setting
-iii. Survey experiment
-conducted on a sample of people randomly selected from a large pop.
-i. laboratory experiment:
-CNN and FOX are the most popular news channels.
-it is difficult to distinguish between news media's reputation and actual bias
in news. They may be both confounding variables -the validity of experimental studies
i. internal validity: internal to the experiment. The degree of confidence in the
causal conclusion drawn from the analysis
ii. External validity: the degree of confidence in genralizability of the causal
conclusion drawn from the analysis
ii. field experiment:
-campaign promises and voter outcome
-like if the promise is job creation, voter out