Q. How do I find the market shares of brands and brand purchase concentration patterns for an industry?

Business Source Premier's Datamonitor industry profiles include market share information for the top companies within that industry. Business Source Premier can also be searched for market share information by combining the search term “market share” with the name of a brand, company or product.

Determining market share, etc. should be covered in your text, but if not there is a sample chapter covering this on the web. It's pretty heavy on theory and light on solid examples, though. The sample chapter is from this book, but we do not yet have it in the library (it's on order).