You've most certainly heard this:
Chances are, he overslept this morning.
I realize the comma is a splice, but it's there only to emphasize the pause that usually accompanies it. When written out, it should probably look like this:
Chances are he overslept this morning.
However, when you read into it, it doesn't make any sense. I would say that using such a clause is grammatically incorrect. Instead, I believe people should be saying:
The chances are high that he overslept this morning.
Am I correct?