A thesis statement should match the type of project being presented. For example, an argumentative legal paper should have a thesis that persuades a reader toward a stated viewpoint. A thesis statement for an analytical science project should provide facts and empirical proof. A thesis statement for an explanatory paper on literature should foreshadow the specific piece of prose researched.
A good thesis develops by posing a question about the research project. For example, suppose a law professor asks his class to write an essay about the reasons people make last wills and testaments. A thesis may begin with the question, "What are the benefits of writing a will?" The question leads the researcher to a thesis statement, such as, "A will eliminates confusion by clarifying a person's last wishes."
A strong thesis statement adopts a definitive position. For example, say a student writes a persuasive paper on the necessity of the Civil War. A strong thesis would take a clear stand, such as, "The Civil War was necessary to maintain the preservation of the United States." A weak thesis statement for the same project may read, "The Civil War may have helped save the United States."
The goal of a thesis statement is to boil the main point of a project down to a short, clear summary. A thesis statement should be limited to one or two comprehensible sentences. It should speak clearly to the heart of the project and assure the audience the project is supported by reliable research.