One’s tense will vary depending on what one is trying to convey within their paper or section of their paper. For example, the tense may change between the methods section and the discussion section.

The grammatical category of tense in English is a bipolar relation based on the feature [±Past]. [+Past] (the so-called present tense) refers to any eventuality that occurs before the speech event ...

Combining have been and were in this way is perfectly acceptable here, Umed. Often, in language use, deciding whether to use the present perfect or the past simple depends on your perspective on the ...