Creating research questions is an important step in the research process. Essentially, a good research question will guide how, where and why you search for particular information. It will guide what information is most important to you.
Your thesis will address your research question. For example, if you are looking at the general topic of income inequality, you might want to develop a question related to the minimum wage.
For example: Are there sound economic reasons why the average CEO is paid 400+ times more than an average company worker?
Once you discover those arguments, then you will form an arguable statement from the question:
"CEOs are in a unique position to add creative value to a company and should therefore be compensated for work at a much higher rate of pay than that of the average worker."
That statement can serve as your working thesis.