It is normal to analyze a dataset in a paper. I am not sure when to use present/past tense to describe how you analyze the data and what your results are. Here I use a short example text to illustrate this:
We analyze the epidemic spreading dataset in 2008. Let I(t) represent the number of individuals that are/were infected at t. I(t) is/was averaged between 1am and 3pm when the spreading is/was stable. Our analysis shows/showed that the epidemic has/had infected 100 individuals, and most of them are/were in EU. The results show that on average each individual has/had three neighbors.
Could you please help decide the tense of the verbs in the above paragraph? It would be good if some explanation is provided.
I ask this, because, I see in many papers, they use the present tense for analysis results of an old data. I am not sure that is correct.