Informational lobbying - the use by interest groups of their (alleged) expertise or private information on matters of importance for policymakers in an attempt to persuade them to implement particular policies - is often regarded as an important means of influence. This paper analyzes this phenomenon in a game setting. On the one hand, the interest group is assumed to have private information which is relevant to the policymaker, whilst, on the other hand, the policymaker is assumed to be fully aware of the strategic incentives of the interest group to (mis)report or conceal its private information. It is shown that in a setting of partially conflicting interests a rationale for informational lobbying can only exist if messages bear a cost to the interest group and if the group's preferences carry information in the 'right direction'. Furthermore, it is shown that it is not the content of the message as such, but rather the characteristics of the interest group that induces potential changes in the policymaker's behavior. In addition, the model reveals some interesting results on the relation between, on the one hand the occurrence and impact of lobbying and, on the other hand, the cost of lobbying, the stake which an interest group has in persuading the policymaker, the similarity between the policymaker's and the group's preferences, and the initial beliefs of the policymaker. Moreover, we relate the results to some empirical findings on lobbying.
