I have completed my MBA in operations management and logistics from UK. Also after completion I have joined family business since last 8 months. But my aim is to pursue a doctorate degree from US or CANADA. Should I go for a DBA or a PHD. I'm a bit confused. Do I need a research proposal before I apply. Also should i search the universities first and then attempt for GRE. I'm planning for applying in spring 2015 or fall 2016. Please help