The Social Value of Public Information When Not Everyone is Privately Informed

When there is strategic complementarity and all agents have access to public information, but only a subset of them has access to private information, strategic complementarity within the subset of privately-informed agents enhances the focal power of public information. This results to an expected social welfare function that is convex in the precision of both private and public information. The welfare gain from increasing the precision of the public information always exceeds the welfare loss from the underutilization of private information by a subset of agents. The results support the use of public information campaigns to change agent behavior regarding risky health behavior, public health crises and social injustices. The findings are robust to several extensions such as biased perceptions about public signals and costly acquisition of private information