[aledalgrande]

Yeah but depending on the data you might have even worse results, selecting the right subset to be representative is really important.

[jhgb]

Would a random sample be representative? Statistically this seems to be the case for any large N. In fact it's not clear to me that any other sample would be more representative.

[aledalgrande]

Many public datasets have skewed classes so if you take a random approach you're not gonna have a good result. And N might not be big enough anyway.