This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Cronbach alpha is a measure of 
Select and explain. 
A. Internal consistency, B. Content validity, C. Central tendency, D. Standard deviation
A: Internal consistency
Answer: A: Internal consistency 
Explanation: Cronbach alpha / Guttman's lamdba 3 :

Is measure of internal consistency.
Value lies between 0 to +1.
Value +0.7 or more is considered satis factory.