Question

Indicate whether the method described below of collecting data is biased or not. If it is biased, suggest one type of bias taking place and explain your answer in a brief sentence.

In the spring, a researcher wants to count the population of the stink bug, an invasive species. She goes into a residential neighborhood and asks residents how many bugs they have seen in the last week.

Answer 1

• Non-response bias could occur as the residents would not have noticed or paid attention to the bugs they observed. Also they would not precisely remember number of bugs observed giving a rough estimate. This can be solved by informing them before the start of week to keep track of the number of bugs they had seen so that they can answer correctly. Other problem here is that the same bug could be seen again and again and counted leading to over-estimation.
• as the researcher is covering only one residential neighborhood, under-coverage bias can occur as other areas that would have larger population of the bugs would be ignored. Increasing the coverage area would prove to be helpful.