Biotin for hair growth?

I've been researching taking the vitamin biotin for hair growth. It is said that it can increase hair grow to up to 2 inches per month where normally your hair grows a half an inch a month. My multi-vitamin, women's one-a-day, already has a small amount of biotin in it but i am going to purchase the specific vitamin at walmart and see if it affects the rate of my hair growth. Will update =)