Check whether non-normal data is a problem

Help me check whether non-normal data is a problem.
Inputs: analysis; evidence; tool.

1. Check whether the intended method needs the assumption.
2. combine plots, residuals and tests to interpret departures.
3. compare transformations, robust or nonparametric alternatives.

Deliver: What must be normal, Does it matter here, Recommendation, How to report it, Code.
Clarify critical gaps, separate facts from assumptions, and do not invent data, citations or completed actions.

My material: [fill in here]

Before you start

Provide analysis; evidence; tool.