This is a hugely helpful idea for the [R] tag and I suspect any other statistics/data-heavy tags as well.
We strongly recommend our users include sample data:
How to make a great R reproducible example
Often due to the nature of the statistical beast even carefully culled sample data is unwieldy. For instance this well-conceived post:
There's simply no way to include the variety of examples the questioner was interested in without a huge code dump. I tend to put mine at the end, but it's still a sub-optimal solution that makes answering harder and the site less beautiful.
