There is not one specific tense that chapter 3 should be written in. It will depend on the sitaution. Note the following key points to assist with tense use for chapter 3:

1. Your school-specific Dissertation Guide may instruct you to write Chapter 3 in the past tense. In the writing process, though, you may find that the chapter requires a mix of the literary present as well as present, past, and future tenses.
2. In particular, the final published dissertation reflects the completed research project. Chapter 3 therefore tells readers what you did, not what you planned to do.
• Remove mention of the proposal or the proposed study. Since the research project has been completed, it is no longer in the proposal stage.
• Look for future-tense verbs, as in (will + main verb) or (will be + main verb). Because Chapter 3 details the steps in your completed research process, you must now use the past rather than the future tense when referring to these steps. For example, use “Participants were required to sign an Informed Consent form” rather than “participants will be required to sign an Informed Consent form.” Likewise, write, “The researcher obtained IRB approval” rather than “The researcher will obtain IRB approval.”
• Remember that other tenses may be necessary, and you may already be using them correctly. However, when discussing the specific process and execution of your own completed research project, the future tense is neither appropriate nor correct.