Probability & Statistics - Identifying Bias - Samantha Leone | Library

Instructions

For each of the following situations involving samples and surveys, identify the primary source of bias. 
Sampling Bias: Non-response bias, Voluntary response bias, under-coverage
Survey Bias: Response Bias (includes question wording, anonymity, or other issues with the survey itself)

Required

1

A total of 300 people participated in a free 12-week weight-loss course at a community health clinic. After one year, administrators emailed each of the 300 participants to see how much weight they had lost since the end of the course. Only 56 participants responded to the survey.

Required

1

Marcos asked a random sample of 50 mall shoppers their weight. Twenty-five of the shoppers were asked directly and the other 25 were asked anonymously using a "secret ballot".

Required

1

A survey posed the following question, "Some cell phone users have developed brain cancer. Should all cell phones come with a warning label explaining the danger of using cell phones?"

Required

1

David hosts a podcast and he is curious how much his listeners like his show. He decides to start with an online poll. He asks his listeners to visit his website and participate in the poll.

Required

1

A senator wanted to know about how people in her state felt about internet privacy issues. She conducted a poll by calling 100 people whose names were randomly selected from the phonebook (note that mobile phones and unlisted numbers aren't in phonebooks). The senator's office called those numbers until they got a response from all 100 people chosen.

Required

1

A high school administration wanted to know what percent of students smoke cigarettes. Randomly selected students were asked by their school counselors when they met to schedule classes for the next semester.

Required

1

Parade magazine posed the following question to its readers, "Should drivers be banned from using all cell phones?" Readers were encouraged to vote online at parade.com.

Required

1

Before the 1936 US presidential election, a popular poll predicted that Alfred Landon would comfortably win against Franklin D. Roosevelt. The poll randomly sampled people from sources like telephone and car registration records, but the country was in an economic crisis, so many voters without those luxuries were not included in the poll.
Voters with lower incomes favored Roosevelt, who ultimately won with 62% of the vote—one of the largest margins of victory ever in a US presidential election.

Required

1

A polling firm wants to contact a random sample of people likely to vote in an upcoming nation-wide election. They will use a random digit dialer to generate and call phone numbers at random, so the poll will include people with landlines, unlisted numbers, and mobile phones.
The random digit dialer skips invalid phone numbers. If a person doesn't answer a call, the dialer will try one more time, and then skip that number.