Statistics Bias

How can bias in statistics be minimized?

• Using random sampling, ensuring a representative sample, and being transparent about the data collection process

• Using a small and unrepresentative sample

• Not being transparent about the data collection process

• Only using non-random sampling

The organizer of a 5K race wants to know how many miles per week runners typically run. To investigate, she surveys the first 30 people who check-in at her race. Which of the following statements is true?

• This is a voluntary response sample. It will likely overestimate the number of miles that runners typically run.

• This is a voluntary response sample. It will likely underestimate the number of miles that runners typically run.

• This is a convenience sample. It will likely overestimate the number of miles that runners typically run.

• This is a convenience sample. It will likely underestimate the number of miles that runners typically run.

Volunteers for a politician's campaign called 100 randomly selected citizens to conduct a survey. Only 50 people agreed to answer the survey questions, and most of them were supporters of the candidate. This is an example of...

• Voluntary Response Bias

• Nonresponse Bias

• Undercoverage Bias

A sample that is not representative of the population is considered __________________.

• Systematic

• Equally likely

• Stratified

• Biased

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.

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.

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.

A radio station is discussing a controversial policy enacted by the local police department. They poll listeners by having them call in to the radio station. Which of the following is the most significant source of bias?

• Leading questions on the survey

• Voluntary Response Bias

• Survivorship Bias

• Undercoverage

A sample should be

• representative of  only middle school students only

• a very large group

• representative of the population

• representative of people who volunteer

Elise, a supermarket employee, approached 50 random customers and asked whether they would be willing to discuss what they like most about the store.  She interviewed the 22 who said yes.  Is this sample of the supermarket's customers likely to be biased?

• yes

• no