Media bias Sendhil mull Andrei shleifer (MIT and NBeR (Harvard University and NBER) October 1. 2002 abstract There are two different types of media bias. One bias, which we refer to as ideology, cts a news out lets desire to affect reader opinions in a particular direct ion. The second bias, which we refer to as spin, reflect s the out let's attempt to simply create a memorable story. We examine compet it ion among media out lets in the presence f these biases. Whereas compet it ion can eliminate the effect of ideological bias, it act ually exaggerates the incentive to spin stories. We are extremely grateful to Alberto Alesina, Gene D'Avolio, Ed Glaeser, Simon Johnson, Larry Katz and richard Posner for comments. e-mail: mullain @mit. e du and ashleifergharvard eduMedia Bias Sendhil Mullainathan (MIT and NBER) Andrei Shleifer (Harvard University and NBER) October 1, 2002 Abstract There are two dierent types of media bias. One bias, which we refer to as ideology, re ects a news outlet's desire to aect reader opinions in a particular direction. The second bias, which we refer to as spin, re ects the outlet's attempt to simply create a memorable story. We examine competition among media outlets in the presence of these biases. Whereas competition can eliminate the eect of ideological bias, it actually exaggerates the incentive to spin stories. We are extremely grateful to Alberto Alesina, Gene D'Avolio, Ed Glaeser, Simon Johnson, Larry Katz and Richard Posner for comments. e-mail: mullain@mit.edu and ashleifer@harvard.edu. 1