A brief one-page summary has just been published in the Academic Medicine: Journal of the Association of American Medical Colleges, which provides a concise overview of the differences between quantitative and qualitative methodologies.
This one pager is a handy starting point to help you make decisions on how to frame your next research study or program evalutation activity.
Castillo-Page L, Bodilly S, Bunton SA. AM Last Page: Understanding Qualitative and Quantitative Research Paradigms in Academic Medicine. Acad Med. 2012 Mar;87:386.