Prepared by Dr. Agatha Shaw, Valencia College, 9/19/2007

http://faculty.valencia.cc.fl.us/ashaw

QUICK REVIEW: CLAST SKILL II.D.2

Choose the most appropriate procedures for selecting an unbiased sample

Some Guidelines:

* Population: The entire group of individuals or instances.

* Sample: A representative subset of a population.

* Simple random sample: Every possible sample has an equal chance of being selected.

1. A sea-food restaurant needs to estimate the average number of customers in its city. The restaurant

decides to conduct a survey. What procedure would be most appropriate for selecting a statistically

unbiased sample?

a) Survey a random sample of the people who work at a local factory.

b) Randomly select geographical regions in the city and then survey a random sample of

people within the region.

c) Select the largest shopping mall in the city and survey a random sample of its visitors.

d) Survey all the students of the largest community college in the city.

2. A blogger wants to find out which topics are popular with students. The blogger decides to conduct

a survey of a sample of students. What procedure would be most appropriate for obtaining a

statistically unbiased sample of the college’s students?

a) Survey the first two hundreds students from an alphabetically listing in the student directory.

b) Have students voluntarily submit a survey through the internet.

c) Survey a random sample of students from the computer lab.

d) Survey a random sample of students from a directory of the entire student body.

3. A local long-distance company needs to find out which features are popular with family in its area.

The company decides to conduct a survey. What procedure would be most appropriate for

selecting a statistically unbiased sample?

a) Survey a random sample of families at a largest grocery store in the area.

b) Randomly select a subdivision in the area and then survey a random sample of families

within the subdivision.

c) Have families voluntarily mail in their preferences.

d) Survey all families of the largest subdivision in the area.