4.05 Sampling

To find out what percent of people in a town approve of plans to convert a meadow into a shopping mall, a reporter goes to a nearby mall and asks every fifth person he sees.

What is the bias of the situation?

• There is no bias. Everyone had the same chance.

• There is biased sampling due to the location where people were asked.

• There are biased answers due to the number of people being asked.

A magazine editor wants to know what percent of people ski. She chooses people randomly on a winter weekend and calls them at home to ask whether they ski.

What is the bias in this situation?

• There is no bias. Everyone had the same chance.

• There is biased sampling due to the number of people asked.

• There are biased answers due to when during the week the sample was taken.

An apartment manager is giving away coupons for $50 off a month's rent. He writes each apartment number on a slip of paper. He puts the slips of paper into a box, mixes them up, and picks 10 slips of paper without looking. What is the bias of the situation?

• There is no bias. Every apartment number had the same chance.

• There is biased sampling due to the number of apartments.

• There are biased answers due to the time of day when the sample was taken.

The owner of a baseball stadium wants to estimate the percentage of people attending a game who are in favor of raising ticket prices by 10% in order to make improvements to the stadium.

Which sampling method will give the owner the best estimate?

• Randomly select 100 of the owner's employees to survey.

• Randomly select 100 seat numbers in the first two rows of the stadium and survey the people sitting in those seats.

• Randomly select 100 seat numbers in the stadium and survey the people sitting in those seats.

• Randomly select 100 season ticket owners to survey.

Keith wants to predict the number of baseball fans who like a specific team. Which sample is better for making this prediction?

• Sample A: A random sample of 10 baseball fans.

• Sample B: A random sample of 100 baseball fans.

The manager of a grocery story wants to estimate the percentage of his customers who like orange juice. He surveys the first 10 customers on a Monday morning.

Which statements are true?

Select each correct answer.

• The manager's sample is unlikely to be biased because the first 10 customers on Monday morning represent all of his customers.

• The manager can improve his estimate by surveying 50 customers instead of 10.

• The only way the manager can estimate the percentage is to ask every customer throughout the week.

• The manager can improve his estimate by randomly selecting customers throughout the week.

A football coach wants to estimate the number of people in his town who plan to purchase season tickets.

Which sampling method will give the coach the best estimate?

• Randomly select 50 names from a list of town residents.

• Randomly select 50 of the players' family members.

• Select the first 50 people who attend the next game.

• Randomly select 50 customers at the local sporting goods store.

The manager at the new radio station in town wants to know what kind of music is popular in the area. She surveys people at random as they exit a supermarket between noon and 2 p.m. on a Monday.

What is the bias of the situation?

• There is no bias. Everyone had the same chance.

• There is biased sampling due to the number of people asked.

• There are biased answers due to the time of day when the sample was taken.