People often don't believe statistical conclusions if there isn't a graph of the data that clearly shows the same result, even (especially?) experienced statisticians.
Why is this? What is statistics for if we can't count on it to be reliably better than just staring at data?
The best hypothesis I have is that a graph is a way to integrate out degrees of freedom in the analysis. It lets you see whether any choices seem arbitrary, and whether different choices might have changed the result.