Does this sentence mean that some data was collected (in the certain point in the past), then has been analysed and interpreted (in the period of the time in the past)?
Should this sentence be written:
The collected statistical data have been analysed and have been interpreted thoroughly.
If you want to signal a past time but not when in relation to the present time:
The collected statistical data have been analyzed and interpreted thoroughly.
No need to repeat have been. It is past tense but vague about when.
If you want to signal something done in the past, unconnected to what is called the time of speaking, use simple past..
The collected statistical data were analyzed and interpreted thoroughly.
No need to repeat were. Here, it would be something like: last week, last month, last year.
