This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Normal Distribution, Skewed Distributions, Subject name: Social & Preventive Medicine
Variation of Sample mean from Population mean is: 
Select and explain. 
A. Standard error of the mean, B. Standard error of propoion, C. Standard error of difference between two means, D. Standard error of difference between two propoions
A: Standard error of the mean
Answer: A: Standard error of the mean 
Explanation: Standard error: It is the variation of sample mean from population mean. Sample mean is known as statistic. Population mean is known as parameter. - Standard detion is the variation in a single value from the mean of a sample.