A doctor wants to know if her patients are happy with her. She decides to survey a sample of her clients.
To choose a random sample from her patient list, she must choose the patients randomly. For this she can assign numbers to her patients like 1 to 300 and then randomly draw numbers from the list either by herself or by number generator. She can choose 30 to 40 percent of her patients randomly for conducting this survey.
This type of random selection is completely random and non biased.
