A research paper is not an essay that wanders toward a conclusion; it follows a fixed structure so readers can find the question, the method, the evidence and the claim in the same places every time. That structure is usually called IMRaD: Introduction, Methods, Results and Discussion.
Worked example: a reader who doubts a study's claim does not re-read the whole paper. She goes to Methods to check how the data were collected, then to Results to see what was actually found, then to Discussion to see whether the claim goes beyond the evidence. A paper that hides its method in the conclusion fails this reader, however good its results.