Theses can be divided into two types: descriptive and prescriptive. In a prescriptive thesis, a writer makes an argument about how something should be. Therefore, a prescriptive thesis focuses on topics such as morality, questions of value and ethics. In contrast, a writer composing a descriptive thesis writes about how something already is. (See Reference 3.)
A thesis paper relies on research, not opinion, to prove an argument. Thus, before composing a thesis paper you must complete research. Use research which provides analysis, measurement and interpretation, regardless of the thesis format (see Reference 3). For example, use research like statistics to prove a hypothesis. Be sure to document all your references in a bibliographical format and cite them in the text, according to the style requirements your instructor has given.
A thesis statement appears within the introduction of a thesis paper. Typically, the statement consists of one sentence which gives the reader an indication of what to expect from the thesis paper. In a thesis statement a writer must make a claim or argument which others may dispute (see Reference 1). The argument acts as the foundation of facts and proof offered throughout the paper. Thus, a thesis statement isn't a question posed to a reader, but a declarative sentence (see Reference 3). For example, a writer's thesis topic about television violence causing crime may have a statement such as "Watching violence on television causes juvenile crime."
A thesis statement must consist of a single argument and be coherent. The reader should clearly understand what the writer is arguing. Also, the thesis paper can't abandon the argument halfway through the paper. A complex thesis which includes interrelated parts is acceptable, as long as it's clear how the different parts relate to each other, explains the Shoreline Community College website. For instance, you can write a thesis statement which includes more than one argument, but they must be closely connected. (See Reference 3.)