Each school will ask you to write a personal statement. While the prompts vary across schools, generally a personal statement will ask you to describe your research interests, qualifications, and career goals.
Schools vary in their importance of the personal statement, but it is an area that students tend to have a lot of questions about.
The personal statement should be clear and well-written. Be realistic about your career goals. While showing interest in research in economics is important, don’t spend too much time describing your passion for economics. This will be unlikely to persuade admissions committees. Get to specifics as soon as possible.
For example, be as specific as possible in describing your past research and course experiences. For example, instead of writing, “I was a research assistant to Professor X and learned a lot through that experience”, spell out exactly what you did. Did you implement data analysis for Professor X? Was that analysis based on a recent methodological advance that you needed to figure out? What type of analysis was it? How did you solve the problems that occurred when implementing the analysis? Be as specific as possible. If you relied on coursework (for example, you proofread and edited a proof in a paper), mention the mathematical background that allowed you to accomplish this task.
You should describe potential research interests, but you don’t need to know exactly what you would like to research in graduate school. Interests change, and it is unlikely admissions committee will place tremendous stock in the specifics of your research proposal. In describing potential research, you should write clearly about your interests and show that you understand how to discuss a potential research project in economics. You can ask an advisor or letter-writer to look over your personal statement.