Sampling and Bias

To study the amount of time students spend doing homework each day, use a random number generator to select 25 students from the student enrollment database to survey.

• Convenience Sample

• Simple Random Sample

• Stratified Random Sample

• Interval Sample

Assign each car in a dealership a number and then use a random-number table to select the cars to be inspected. 

• systematic

• random sample

• convenience

• biased sampling

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

Carlos wants to know the favorite sport of people at his school so he asks his baseball team.

• Biased

• Unbiased

You want to know what the favorite lunch option of 9th graders at WMHS is. You ask 9th graders who want to participate to go to the office 5th period to complete a survey. This is...

• Biased, because it is a convenience sample

• Unbiased

• Biased because it is an interval sample

• Biased because it is a voluntary response sample

True or False: all samples lead to a good prediction about an entire population.

• True

• False

Ana wants to know the average student’s opinion of the tardy policy at her school. Which group of students should she survey in order to achieve the most accurate results?

• Thirty randomly selected students from her school

• Thirty students who are rarely tardy

• thirty of her friends

What would be the sample in this example?
Surveyors in a mall choose shoppers to ask about products they prefer.

• the surveyors

• all shoppers in the mall

• the shoppers who were asked their preferences

During a school survey conducted by Anika, which type of bias occurs when some students are less likely to be included in the sample than others?

• Selection bias

• Response bias

• Non-response bias

• Measurement bias

Which of the following is an example of selection bias?

• Luna conducts a survey only in urban areas, excluding rural areas.

• Priya conducts a survey, and all participants respond truthfully.

• Elijah conducts a survey, and responses are recorded accurately.

• A survey is conducted, and participants are selected randomly.