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
Square root of detion is also called as ? 
Select and explain. 
A. Standard detion, B. Standard error, C. Mean detion, D. Range
A: Standard detion
Answer: A: Standard detion 
Explanation: Ans. is 'a' i.e., Standard detion o Standard detion is square root of mean detion, so it is also known as "Root - means - square - detion". o The steps for calculating SD are ? a) First calculate mean (y) b) Then deduct this mean from each value to obtain detion from mean (x - .T) as we did in calculating mean detion (see above). c) Now square, each detion (x - )7)2 d) Add up the squared detions --> S (x - 7)2 e) Divide the result by the number of values (observations), i.e. n . f) At the end, take square root, which gives the standard detion.