Simple random sampling

Problem:



Solution:

A good question to ask!

To do a simple random sampling, you need to make sure you know the martial and health status of all parents (so that you do not randomly sampled a person who is not accessible). With the population perfectly known, you generate sample without replacement in the population and do the study with that sample.

To do convenience sampling, you simply wait outside the door at the school. By the time parent comes pick up the student, you just ask. See how much simpler this is than the approach above? The approach, however, is not as good as simple random sampling as one might expect. You may miss all busy parents who do not pick up their children punctually.

To do voluntary response sample. You simply ask every student to take home a questionnaire. Parent may voluntary give answers, that is voluntary response sampling technique. This is also simple, again, bias towards parents who are more free and willing to do questionnaire.