Sample Surveys and Experiments

Mrs. Boyd wants to find the average height of all her students in her classes. She decides to use the first 5 people who walk in the door. Is this a good representative sample?

• Yes

• No

210 college students were randomly assigned to play either a violent or nonviolent video game.  A short time later, the students were presented with the opportunity to trivially harm another person and results comparing the two groups were recorded.
Is this study OBSERVATIONAL or EXPERIMENTAL ? 

• Observational

• Experimental

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

Four groups of randomly selected people are assigned a different diet. After six months, the blood pressures of each group are compared.

• Observational Study

• Experiment

_______ is a part of a group being surveyed.

• Sample

• Population

• Random Sample

• Quartile

Rats with cancer are divided into two groups. One group receives 5 milligrams of a medication that is thought to fight cancer and the other receives 10 mg. After 2 years, the spread of cancer is measured.

• Observational Study

• Experiment

Ms. Joy wants to find the average height of all her students in her classes. She decides to use the first 5 people who walk in the door. Is this a good representative sample?

• Yes

• No

Ms. Robinson is conducting a survey to find out the favorite snack of ninth and tenth graders. She will ask a sample of 100 students. Which of the groups below should be surveyed to get the BEST representative sample?

• 20 students from each of the 5 local high schools.

• The first 100 students who go to a local baseball game

Which of the following is not a way to choose a random sample of 25?

• Assign numbers. Use a random number generator to choose 25

• Put names in a hat, mix them up and choose 25

• Assemble possible participants in a circle around a person who is blindfolded,  spin the person around 3 times and have them point at a person.  Do this 25 times.

In a certain school, students can choose whether to eat in the school’s cafeteria. A reporter working for the school’s newspaper polled students on their reactions to changes in the menu at the cafeteria. For each student leaving the cafeteria in one 20-minute time period, the reporter used a die to determine whether to stop the student and ask how he or she felt about the new menu. In the reporter’s article it was stated that a random sample of the students showed that 23% of the school’s student population was happy with the new menu. Which of the following statements is true?

• Because each student leaving the cafeteria was randomly selected and could choose to answer or not, this is a random sample of the student population, and the 23% is an accurate measurement of the school population’s view of the new menu.

• Because students self-selected whether to eat in the cafeteria, the sampling method might be biased and the sample might not be representative of all students in the school.

• The survey would have been more effective if the reporter had collected the data in one 10-minute time period rather than in one 20-minute time period.

• The survey would have been more effective if students who cared about the food could have called the reporter to tell how they felt about the new menu, so that only students with opinions on the subject would have been surveyed.

• Because no treatment was imposed on the students eating in the cafeteria, one cannot make any conclusions about the new menu.