Sampling Methods

You have probably seen the mall interviewer, clipboard in hand, approaching people passing by. To estimate the mean amount of money that city residents plan to spend on holiday gifts, the interviewer surveys 100 mall shoppers. 

Why is this sampling method is biased?

• The sampling method (convenience sampling) is biased because the people at the mall are there to spend money.

• The sampling method (convenience sampling) is biased because this is an observational study. 

• The sampling method (voluntary response sampling) is biased because the people at the mall are there to spend money.

• The sampling method (voluntary response sampling) is biased because this is an observational study.

You have probably seen the mall interviewer, clipboard in hand, approaching people passing by. To estimate the mean amount of money that city residents plan to spend on holiday gifts, the interviewer surveys 100 mall shoppers. 

Is the mean amount reported by the people in the sample likely greater than or less than the mean amount that all city residents plan to spend?

• The mean amount reported by the people in the sample is likely

  greater than the mean amount that all city residents plan to spend

• The mean amount reported by the people in the sample is likely

  less than the mean amount that all city residents plan to spend

Many websites include customer reviews of products, restaurants, hotels, and so on. The manager of a hotel was upset to see that 26% of reviewers on a travel website gave the hotel a “1 star” rating—the lowest possible rating.

Explain why this sampling method is biased.

• This sampling method (voluntary response sampling) is biased because it is likely that the customers who chose to leave reviews feel strongly about the hotel, often due to a bad experience. 

• This sampling method (convenience sampling) is biased because it is likely that the customers who chose to leave reviews feel strongly about the hotel, often due to a bad experience. 

• The sampling method (voluntary response sampling) is biased because this is an observational study.

• This sampling method (convenience sampling) is biased because it is likely that the customers that chose to leave reviews feel strongly about the hotel, often due to a bad experience. 

Many websites include customer reviews of products, restaurants, hotels, and so on. The manager of a hotel was upset to see that 26% of reviewers on a travel website gave the hotel a “1 star” rating—the lowest possible rating.

Is 26% likely greater than or less than the percentage of all the hotel’s customers who would give the hotel 1 star?

• The percentage of 1’s in the sample is likely

  greater than the percentage of all the hotel’s customers who would give the hotel 1 star.

• The percentage of 1’s in the sample is likely

  less than the percentage of all the hotel’s customers who would give the hotel 1 star.

Sammy wants to know what percent of students at her high school have a driver’s license. She surveys all students in her statistics class and finds that 68% of the students in her sample have a driver’s license.

What type of sample did Sammy obtain?

• A random sample

• Voluntary response sample

• Convenience sample

• A census

A University of Helsinki (Finland) study wanted to determine if chocolate consumption during pregnancy had an effect on infant temperament at age 6 months. Researchers began by asking 305 healthy pregnant women to report their chocolate consumption. Six months after birth, the researchers asked mothers to rate their infants’ temperament, including smiling, laughter, and fear. The babies born to women who had eaten chocolate daily during pregnancy were found to be more active and “positively reactive”—a measure that the investigators said encompasses traits like smiling and laughter.

Is this an observational study or an experiment? Explain your answer.

• This is an experiment. There were no treatments imposed on the healthy pregnant women.

• This is an experiment. There were treatments imposed on the healthy pregnant women.

• This is an observational study. There were no treatments imposed on the healthy pregnant women.

• This is an observational study. There were treatments imposed on the healthy pregnant women.

A study of child care followed 1364 infants through their sixth year in school. Later, the researchers published an article in which they stated that “the more time children spent in child care from birth to age four-and-a-half, the more adults tended to rate them, both at age four-and-a-half and at kindergarten, as less likely to get along with others, as more assertive, as disobedient, and as aggressive.”

Is this an observational study or an experiment? Explain your answer.

• This is an experiment. There were no treatments imposed on the infants.

• This is an experiment. There were treatments imposed on the infants.

• This is an observational study. There were no treatments imposed on the infants.

• This is an observational study. There were treatments imposed on the infants.

Identify the sampling method:

Zoe surveyed shoppers in the supermarket's bakery sections about their purchasing habits.

• Voluntary

• Convience

• Simple Random Sample

• Cluster

• Stratified

Identify the sampling method:

1. Charles, the host of a radio show, asked his listeners to call in and tell him what they thought about school uniforms.  

• Voluntary

• Convience

• Simple Random Sample

• Cluster

• Stratified

Identify the sampling method:

1. Gavin surveyed every 10th person who entered the Comicon Convention. 

• Voluntary

• Convience

• Simple Random Sample

• Cluster

• Systematic