Stats are ranked in 8 categories...
The least someone can get in each category 0.5 points and the most someone can get is 5 points, all points are in 0.5 intervals (.05, 1, 1.5, etc...). The total is out of 40 points, the highest stat a ninja could receive is 35.5/40, which only Jiraiya and Itachi have.
Here's a guide that can help decide the scores in each category (These are approximations)...
.05-1.5 = Below Average
2 = Decent
2.5-3 = Average
3.5-4 = Above Average
4.5-5 = Excellent
The character's stats were contained in the First, Second, and Third Databooks. Each databook was based on diff