An opinion thesis is exactly what it sounds like: a thesis based on the writer's opinion. However, in a research paper, the opinion comes from analyzing evidence and information gathered from academic sources. For example, a writer could analyze academic sources that detail the life of Mozart. The writer can form an opinion based on the information and develop a thesis that states the writer's desire to prove his opinion correct.
A category thesis details the category and reason a person, place, event or phenomena fits within a certain category. For example, this type of thesis could categorize an author's work into a certain genre or literary style. It could categorize an event or phenomena into a certain movement. A category thesis might say, "Poet Mohja Kahf's work can be categorized as feminist based on her female empowering content, feminine style and powerful voice." The writer is indicating in this thesis that Kahf's writing is feminist, and the writer will prove so by discussing the mentioned details about Kahf's work.
A critique thesis will introduce one topic and in the same sentence critique the topic by emphasizing another issue. An example of this style might be, "Mohja Kahf is a talented poet, but as a novelist she fails in certain aspects." The topic of Mohja Kahf as a poet is first introduced, but then Kahf is critiqued with another issue, her work as a novelist. This thesis style is mainly used so the writer can compare and contrast two topics/issues or critique a topic in one issue and validate it with another.
An ethnographic-based thesis is a style that can use the technique of other thesis styles but differs based on the evidence and source information. Ethnographic research is gathered evidence based on human subject interviews or anthropological observation. An experiment thesis refers to a thesis that is developed based on scientific experiments the writer conducts himself. Such thesis ideas are a category of their own because they rely on research-based but controversial evidence. The research is controversial because the evidence has not been verified before the current paper. These types of thesis statements are generally unique.