aim: how do we identify biased samples and surveys? do now

Aim: How do we identify biased samples and surveys?Do Now

Aim: How do we identify biased samples and surveys?The student council wants students to help decide on a theme for a costume dance. Students can choose one of the councils three ideas from the options listed below.

Dance Theme Survey

Which dance theme do you prefer?

Choose one:

moviesfamous historical figures sports and games

Dance Theme Survey

Which dance theme do you prefer?

Choose one:

moviesfamous historical figures sports and games

Surveying all of the students will take too long .

Some of the students will be surveyed.

Aim: How do we identify biased samples and surveys?

One way to collect data about a group is by doing a survey.

population – the entire group of people or objects that you want information about.

unbiased sample– a sample that is representative of the entire population

biased sample– a sample where one or more parts of the population receive greater representation than others

sample– a part of the entire population. Larger samples are more reliable than smaller samples.


Tell whether sample is biased or unbiased. Explain your reasoning.

1) Survey members of the movie club.

2) Survey students as they enter the school.

3) Survey students on the football team.

Biased Sample. This group is more likely to want the movie theme.

Unbiased Sample. This is a wide range of students.

Biased Sample. The football players are more likely to prefer the sports and games theme.

Biased Samples


A fast-food franchise is studying whether to open a new restaurant in town. A sample of residents will be surveyed. Tell whether the sample is biased or unbiased. Explain your reasoning.

1) Survey customers in a diner.

2) Survey patrons in a library.

3) Survey customers in a grocery store.

Biased Sample. Diner customers are more likely to favor fast-food.

Unbiased Sample. They are neither likely or unlikely to favor fast-food.

Biased Sample. Grocery store customers could be less likely to favor fast-food.

Biased Samples


It is important to make sure that the questions are not biased. Questions should not assume anything or influence the answers.

Will these questions produce a biased results? Explain.1) How many hours of television do you watch per day?

2) Do you think filthy rich people should pay more in taxes.

Unbiased Question. This will not produce biased results.

Biased Questions

Biased Question. The questions encourages a response of yes by using negative language to describe rich people.


It is important to make sure that the questions are not biased. Questions should not assume anything or influence the answers.

Will these questions produce a biased results? Explain.1) Do you support the unfair rule of requiring students to do a long community project? Yes [ ] No [ ]

2) Do you like our new apple-nut yogurt flavor, now on sale in stores everywhere? Yes [ ] No [ ]

Biased Question. The questions states that the rule is unfair and encourages a response of ‘no’.

Biased Questions

Biased Question. The questions assumes the person has tried the flavor. If you have not tried the yogurt you may not give an accurate opinion.


Practice: Tell whether sample is biased or unbiased. Explain your reasoning.

1) To determine the kind of snacks people like to eat, every tenth person who walks past a park entrance is surveyed.

Unbiased Sample. This group is random.


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aim: how do we identify biased samples and surveys? do now

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