Bias can take many forms. Sometimes it is created unintentionally by conditions in an experiment. Other times it is more intentional. For each example below, comment on possible bias.

1. In a TV commercial an interviewer asks people on the street to each name his or her favorite radio station. All five respondents chose the same station as their favorite.

   Possible answer (a):

   They did not show the people who named other stations.

2. A university campus wants to increase fees in order to build a new recreation hall. It surveys students to determine support. Survey booths are placed outside the university gym. The resulting survey showed overwhelming support.

3. A study shows that many more accidents occur on I-95 during the day than at night. Is it therefore safer to drive at night?

4. An active citizens’ group claimed that a nuclear facility was operating at below average safety levels and therefore should be shut down.

   Answer (d):

   About half of all power plants are below average. It does not mean that it is unsafe.