Cronbach Alpha?

Question

Cronbach Alpha? please give a brief definition and use of it.

Answer 1

It is basically a measure of to what degree different items on a test instrument measure the same variable. 0 is completely unreliable, and 1 is perfectly reliable.

For example, if on a test I had 3 questions that were all supposed to test for some personality trait, a high alpha (usually 0.7 or above) would indicate that the three all measured the same thing. A low alpha would indicate that the questions are not necessarily measuring the same thing.

Answer 2

http://en.wikipedia.org/wiki/Cronbach's_alpha