I found this paper helpful in creating a scale to measure SE. It is a review of Measurement instruments to measure Bandura's self- efficacy concept. It's by Usher and Pajares, 2008.
If you read the article "Effects of management by objectives : studies of Swedish upper secondary schools and the Influence of role stress and self-efficacy on school leaders" in Journal of Applied Social Psychology you will becomw inspired and get some new knowledge in this area.