Question

Please explain what incorrect population sampling is and provide an example. I am not referring to a small sample size but instead sampling bias or another incorrect use of sampling.

Answer 1

Sampling is typically done to determine the characteristics of a whole population, the difference between sample and population value is considered sampling error. Sampling bias is usually the result of a poor sampling plan. It is the tendency to favour the selection of units that have particular characteristics.

For eg: A shypothetical case where a survey was conducted to find out the stress level that graduates students were going through. A mail questionnaire was sent to 100 randomly selected graduate students. Only 52 responded and the results were that students were not under stress at that time, when the actual case was that stress was highest at that period for all students except those who were writing their thesis at own pace. This is the group that had time to respond. Hence, bias can be very costly and has to be guarded against as much as possible.