Chapter 11 Lesson 1 - Biased and Unbiased Samples

Select the correct option. Decide the type of sampling method the following situation describes.

A teacher wants to know how many hours it takes for all students at the school to complete their homework. She asks the last 2 students that leave her classroom.

• Voluntary response sampling

• Systematic random Sampling

• Convenience sampling

• Simple random sampling

Select the correct option.

Sue is taking a survey about the quality of the science program at her school. She randomly selects 4 students from each science class to participate in the survey.

Her sample is a ___.

• Systematic random sample

• Stratified random sample

• Voluntary response sample

• Simple random sample

Answer explanation

Sue divided the population into groups and then took a random sample from each group.

Select the correct option.

You want to find the number of people in your school that spent more than 4 hours completing their homework. Which sampling method would give the most unbiased results?

• Ask 30 students in your Math class and Science class.

• Ask 30 people that you meet at the mall.

• Ask 30 random students from your school, of different ages.

• Ask 30 friends.

Answer explanation

Sue divided the population into groups and then took a random sample from each group.

Choose the correct statement.

Which sample is a systematic random sample?

• Survey 100 students selected at random.

• Survey every 5th customer that leaves the store.

• Randomly select 5 students from each home room in the school.

• Survey the students sitting at your lunch table.

Answer explanation

Sue divided the population into groups and then took a random sample from each group.

Select the correct option. Decide the type of sampling method the following situation describes.

The sports coach wants to survey students in his after-school dub. In total, he teaches 40 students after school. He places each students' name in a hat, and randomly selects 10 names from the hat.

• Voluntary response sampling

• Systematic random Sampling

• Convenience sampling

• Simple random sampling

A class teacher randomly selects 6 students from his class of 30 to participate in a survey. He assigns each student a number, and uses a random number generator to select the students.

2 students enjoy Art.

3 students enjoy Physics.

1 student enjoys English.

a) Is this a biased or unbiased sample?

• The sample is a random sample and is biased.

• The sample is a systematic sample and is unbiased.

• The sample is a random sample and is unbiased.

• The sample is a systematic sample and is biased.

Choose the correct statement.

Kim takes a survey asking students in her school what their favorite subject is. She three students from each class in her school. The results are shown in the table.

Kim states that Math is the favourite of students in her school. Is this inference valid?

• Yes, because the sample is a stratified sample and is unbiased.

• Yes, because the sample is a stratified sample and is biased.

• Yes, because the sample is a random sample and is unbiased.

• No, because the sample is a random sample and is biased.

Choose the correct statement.

Alan takes a survey asking if the school should increase funding for the IT program. He asks 20 people at his IT school club. The results are shown in the sample.

Alan states that a large number of people support increasing funding for the IT program. Is the inference valid?

• No, because the sample is a voluntary response sample and is biased.

• Yes, because the sample is a convenience sample and is unbiased.

• Yes, because the sample is a voluntary response sample and is unbiased.

• No, because the sample is a convenience sample and is biased.

Select the correct option.

A teacher ask a random sample of 100 students to name their favorite hobby. The results are shown in the table.

The teacher makes the statement that sports is the favorite hobby of the students. Is this a valid inference?

• Yes, because the sample is unbiased and the inference is supported by the data.

• No, because the sample is biased and the inference is supported by the data.

• No, because the sample is biased.

• No, because the inference is not supported by the data.

Select the correct option.

A teacher randomly selects 50 students out of 350 students in grade 7, to take part in a survey about recycling.

She gives each student a number, and uses a random number generator to select the students. Of the 50 students, 10 students recycle their plastic bottles.

This is an example of ___.

• Biased convenience sampling

• Unbiased systematic random sampling

• Unbiased simple random sampling

• Biased voluntary response sampling