A thesis can be broadly classified into analytical papers, expository papers, argumentative papers and narrative papers. It should be specific, clearly stating what will be discussed in the material that follows. The statement should be supported with specific evidence. The thesis statement should provide a roadmap for the entire paper, letting the reader know how the writer interprets the significance of the subject under discussion. For example, the subject of World War I written as a thesis presents readers with a way to understand the war based on the writer's interpretation of it.
Writing a thesis statement begins with finding the appropriate subject matter. Once this is done, the thesis statement can be created. The statement should not be too restrictive or wide-ranging. The writer engages in research, reading and reflection to decide on the point of view that will hold the paper together and the arguments to be presented. For example, the affect of computers in schools is a broad topic that needs to be tailored to narrow the focus in terms of a specific group of people -- first-graders or teachers, time period and geographical area.
A strong and effective thesis statement must restrict parameters to prevent the writer from rambling. A restricted statement keeps ideas and arguments presented in order. To be effective, the statement should be precise and not contain vague language, disconnected thoughts and generalities. The statement should make a claim supported by the evidence presented by the writer, and should be open to debate. A thesis that only states facts is a summary of a topic; readers should be able to challenge and oppose the views presented.
The thesis statement is generally at the end of the introductory paragraph of the thesis to engage the audience early in the argument, set the direction of the paper and state how the argument will be presented. The thesis statement can be anywhere in the paper depending on individual writer styles and material structuring. Some writers prefer to place the thesis statement in the conclusion. In this example, the writer takes readers through a process of logical thinking that ends in drawing a conclusion.