Sampling and Bias

A teacher wants to know the average time spent doing homework by the students in her class of 20 girls and 5 boys.

She selects the five closest to her desk. What type of sampling method is being used?

• simple random

• Voluntary Response

• Convenience

• Systematic Random

Each student in the school is given a different number.  A student is randomly selected from the first 25. That student and every 25^th student thereafter are in the sample.  This is what type of sampling design?

• SRS

• Systematic

• Multistage

• Stratitfied

Which is not a method of random selection?

• Using a table of random digits

• Using a random number generator

• Drawing numbers out of a hat

• Randomly pointing to numbers on a page

I want a representative sample of likely voters. I use a telephone directory to randomly select 200 people. Only 85 people answer their phones to participate in the same. What kind of bias is this?

• Undercoverage

• Nonresponse

• Response

• Voluntary Response

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.

A student wants to know which type of pizza the students at his high school prefer. Which option would give an unbiased sample?

• Asking all the students in the hot lunch line.

• Asking 10 students from each homeroom

• Asking 100 random students, chosen by drawing names from a hat

• Asking all the 10th graders

A sample should be

• representative of  only middle school students only

• a very large group

• representative of the population

• representative of people who volunteer

A tax preparation company wants to see how satisfied its customers are with their services. Which of the following would give them the best unbiased sample?

• looking at customer reviews on their social media page

• questioning the first 25 people that call the company

• asking the last 25 people on an alphabetical list of all of their current customers

• surveying a random sample of customers from a list of all of their current and previous customers

A school chooses 3 randomly selected athletes from each of its sports teams to participate in a survey about athletics at the school. What type of sampling method is being used?

• Simple Random Sampling

• Stratified Random Sampling

• Cluster Random Sampling

• Systematic Random Sampling