Biased vs Unbiased and Sampling Methods

4. A company makes DVDs and randomly selects 25 from 1500 to test them to see if they work.

• Biased

• Unbiased

Nick wants to determine the amount of time seventh-grade students spend studying for their math exam. Which sampling method would be most unbiased?

• Survey the 15 girls in his class.

• Survey 60 seventh-grade students.

• Survey his 3 best friends.

• Survey the 13 boys in his class.

Celia has a large container in which four different kinds of coins are thoroughly mixed. She wants to take a sample of her coins to estimate which kind of coin she has the most. Which of the following methods is the best way for her to select a sample?

• taking one coin from the container

• taking coins until she has one of every kind

• taking ten coins of each type from the container

• taking thirty coins out of the container without looking

To determine how many students plan to attend the school musical, Maria surveys 100 random people in the hallway.

• Biased

• Unbiased

You want to know what is the most favorite sport of 7th graders at BMS. You ask 7th 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 because it is a good question

• Biased because it is an interval sample

• Biased because it is a volunteer sample

• Unbiased because all student have the ability to participate

The Student Council asked every tenth student in the lunch line how they preferred to be contacted with school news. The results are shown in the table. Is this an unbiased sample? If yes, suppose there are 684 students at the school. How many can be expected to prefer E-mail?

• No, it's a biased sample

• 432

• 304

• 16

Dylan wants to know how the students at his school rate the cafeteria.  He surveyed his school's basketball team to rate the school cafeteria. Is this a biased sample of the school's population?

• Yes, because it is a convenience survey

• No, the basketball team has the smartest students

• Yes, because it's voluntary survey

• No, he should have asked the football team

Biased or Random?

Chloe and Danna want to determine the favorite subject of all students in the middle school. So they place every middle school student's name in a bucket and choose 30 to poll.

• Biased sample

• Random sample

To get valid results, a sample must be...

• biased

• unbiased

Carlos wants to know the favorite sport of people at his school so he asks his baseball team. What type of sample would this be?

• Biased

• Unbiased