I've seen a lot of people leave their 2G/3G data connection on the entire day and then complain about the battery life of the phone is minimal. I thought of finding out which among the three viz. Bluetooth, Wi-Fi and 3G eat more battery power in an Android phone and found the PDF that describes this in detail.
The study has been done by Goran Kalic, Iva Bojic and Mario Kusek from University of Zagreb; Faculty of Electrical Engineering and Computing. The linked PDF is a copyrighted material of the authors and therefore we've linked it to the original document website.
Study On Power Consumption In Android Phones When Using 3G, Wireless & Bluetooth 1.0
Paper that presents the findings of study on how 3G, wireless and bluetooth affect Android battery