Population and Bias

Before a nation-wide election, a polling place was trying to see who would win. Which choice best represents a sample?

• A selection of voters over age 50.

• A selection of male voters.

• A selection of voters of different ages.

• All voters.

When a sample does not accurately represent the population it is a:

• Unbiased sample

• Biased sample

Why do we randomly select our samples?

• for control

• reduce bias

• so we don't get the same answers from everyone

• to eliminate confounding results

When a sample does not accurately represent the population it is a:

• Unbiased Sample

• Biased Sample

Tanya wants to know the percent of people likely to attend the upcoming musical at school. She asks each person in the musical how many people they know who are coming to make a prediction. Why is this sample biased?

• Drama students are more likely to lie.

• Musicals are better attended than plays.

• The drama teacher was not asked.

• The sample is not random and not representative of the entire school population.

Answer explanation

The sample is not random and not representative of the entire school population, as it only includes people involved in the musical, leading to bias.

In order to estimate the proportion of students that text while driving, a school administrator selects a simple random sample of students from a list of all students at the school who have parking permits. The students are called to the office, one at a time. The administrator asks each student, “Do you text while driving, even though you are not supposed to?” Based on the survey, the administrator estimates that only 2% of students with parking passes text while driving. What potential bias is present in the design of this survey and what is the likely direction of the bias?

• The sample proportion is likely an underestimate of the population proportion due to response bias.

• The sample proportion is likely an underestimate of the population proportion due to undercoverage.

• The sample proportion is likely an underestimate of the population proportion due to nonresponse.

• The sample proportion is likely an overestimate of the population proportion due to response bias.

• The sample proportion is likely an overestimate of the population proportion due to undercoverage.

The School Dance Committee conducts a survey to find what type of music students would like to hear at the next dance. Which sampling method is least likely to result in a biased sample?

• Call the top 20% of the senior class. 

• Interview every 10^th student as they enter the school.

• Ask every 5^th person leaving a school jazz band concert.

• Set up a hip-hop only website where students can list their 3 favorite songs if they open up the link.

Before a nation wide election, a polling place was trying to see who would win. Which choice best represents the statistic?

• A selection of voters over age 50.

• All voters.

• The percentage of voters in favor of the candidate.

• 53% of the selection of voters support the candidate.

A survey of 1500 American households found that 65% of the household own a computer. Identify the population.

• 65% of American households in the U.S.

• All the American households in the U.S.

• 1500 American households in the U.S.

• 65% of the 1500 American households in the U.S.

A study involving 300 gym-goers found that 45% of them use a fitness tracker regularly. Specify the population.

• The 300 people that go to the gym.

• 45% of the 300 people that use a fitness tracker.

• All the individuals who go to the gym and were part of the study.

• All individuals that use a fitness tracker regularly.