Why is it important to ensure that a population sample is unbiased? In your own words, give an example in…

Why is it important to ensure that a population sample is unbiased? In your own words, give an example in detail of how you would obtain an unbiased sample using one of the techniques listed below. Include two or three precautions you would take to insure that the sample is as unbiased as possible. (Remember to select only one.)
· Systematic sampling
· Cluster sampling
· Stratified sampling