About consistency and uni-dimensionality, these articles explain well:
Gardner, P. L. (1995). Measuring attitudes to science: Unidimensionality and internal consistency revisited. Research in Science Education, 25, 283-9.
Gardner, P. L. (1996). The dimensionality of attitude scales: A widely misunderstood idea. International Journal of Science Education, 18, 913-9.
Yu, C. H. (2001). An Introduction to computing and interpreting Cronbach Coefficient Alpha in SAS. Proceedings of 26th SAS User Group International Conference. [On-line] Available: URL: http://seamonkey.ed.asu.edu/alex/pub/cronbach.html
