Comparative slice finder: disallow non-numeric values as target metrics

[neubig]

I got this confusing result from the comparative slice finder:

This was due to human error where I selected "output" as the target metric, which doesn't make any sense because "output" is a string. It’s not shown in the non-comparative slice finder for some reason, so I don’t know where the consistency comes from.

It would be good to not allow non-numeric values as the "target metric" in the comparative slice finder to prevent this kind of error.

[cabreraalex]

We calculate difference in the comparison view for non-numeric columns as a 1 or 0 same or different. So you can actually use it as a metric column and find slices where the models disagree the most for a given column.

Maybe we can change the name or tooltip to clarify this? Or does that make sense?

[neubig]

Ah, that's an interesting idea! But yeah, changing the name and tooltip would make sense. The tooltip right now specifically says the column is continuous :)