Tenses express the time of events or existence. Tense choices are, to some extent, linked to the different parts of a text, and, in some situations, to the writer’s attitude towards their source. The present instruction is suggestive. For textual fluency and stylistic coherence, it is important to use different tenses accurately and consistently.
The present tense is typically used in the following contexts:
The past tense (or, if needed, other tenses of the past) are used in the following cases:
In the latter example, the significance of the source for the writer is articulated more clearly and with more emphasis
N.B. Use the present tense, instead of the future tense (will + INF), to refer to the subsequent parts of the thesis (“The results of the analysis are presented in Chapter 4”). This is a “pragmatic exception” to the rules governing the use of tenses in English, according to which the future tense is normally used when referring to future action.