Research is essential for public relations to understand how the public perceives an organization and to plan and evaluate PR programs. There are three main types of PR research: applied research which examines specific issues and develops campaigns, basic research which examines underlying processes, and introspective research which examines the field of PR itself. Research informs all aspects of the PR process from defining problems to planning, implementing, and evaluating programs. Evaluation research in particular judges the effectiveness of programs and identifies ways to improve future efforts.