'Hard,' measurable (through a suitable measure such as dollars, degrees, inches, millimeters) and verifiable data manageable to statistical manipulation. Quantitative data defines whereas qualitative data describes.
Ex: The girl is fat. (Qualitative info, because everyone has a different viewpoint as to what "fat" is.)
The girl is 300 lbs., and is 5'3". (Quantitative info, with measurable data, weight and height. Now I can judge for myself if she is truly fat or not.)
I'm one smart-behind college student.