Education leaders in Connecticut say the state is still fine-tuning its new teacher-evaluation system. Some school administrators say the observation process is too cumbersome. "The whole idea of using student test scores ... is really tricky," Superintendent David Title said. "It's conceptually appealing, but it's very difficult to do technically ... There are so many different variables that impact student achievement. ... What you're not able to do, in my view, is prove cause and effect."