How do you know if a sample is unbiased or biased

What makes a sample unbiased?How do you know if the sample mean is an unbiased estimator?If an overestimate or underestimate does happen, the mean of the difference is called a bias. that's just saying if the estimator (i.e.11 examples of biased survey questions negative questions a negative question is a type of question for which a no response indicates an affirmative answer and a yes response indicates a negative answer.A random sample is more likely to be representative of the entire population than other types of samples.

In more precise language we want the expected value of our statistic to equal the parameter.More formally, a statistic is biased if the mean of the sampling distribution of the statistic is not equal to the parameter.Although this procedure reduces the risk of sampling bias, it may not eliminate it.