ewan sez: I would say the opposite of the above though - you have to be efficient before you can be effective. If that were only true. Effective means that an organism has gained the skills necessary to acomplish a predetermined task X number of times. Efficient means the organism has learned a way to use the least amount of energy to get the task done. When you first learned how to drive, it was hard and scary. Now, after a couple of years behind the wheel, you can text, eat a sandwich, dry your nails, check out the GPS, and email your homework to your teacher, all while driving. The organism needs a effective set-up before it should shop for a efficient set-up.