5Q--4-2

Each state conducts an annual study of seat belt use by drivers following guidelines set by the federal government. Seat belt use is observed at randomly chosen road locations at random times during daylight hours. A large number of road locations have been identified in each state’s counties. Maine has 16 counties, and samples were taken in each county with sizes proportional to the number of designated locations in that county, so each road location is equally likely to be selected. What kind of sample is this?

• Simple Random Sample (SRS)

• Stratified sample

• Cluster sample

• Systematic sample

• Quota sample

Which principle of experimental design is used to balance out the effects of lurking, non-explanatory variables that may differ among the subjects of the experiment?

• Comparison

• Random Assignment

• Control

• Replication

• Clustering

Which principle of experimental design is used to filter out the effects of lurking variables in the treatment that may creating confounding in an experiment?

• Comparison

• Random Assignment

• Control

• Replication

• Correlation does not imply causation

Which principle of experimental design is used minimize the effects of environmental variations when conducting an experiment?

• Comparison

• Random Assignment

• Control

• Replication

• Random Selection

A cookie manufacturer is trying to determine how long cookies stay fresh on store shelves, and the extent to which the type of packaging and the store’s temperature influences how long the cookies stay fresh. He designs a completely randomized experiment involving low (64 Fº) and high (75 Fº) temperatures and two types of packaging—plastic and waxed cardboard. What are the factors in this experiment?

• packages of cookies

• temperature and packaging

• low temp and plastic, high temp and plastic, low temp and waxed cardboard, high temp and waxed cardboard.

• the store shelves

• the cookie manufacturer

A medical research team looked up lung cancer rates from a neighborhood located near a downtown paper mill to lung cancer rates from a neighborhood far out in the suburbs. The results clearly showed much higher instances of lung cancer in those from the downtown neighborhood. Which of the following is the best answer to the question "Do the researchers conclude that proximity to the paper mill is causing lung cancer?"

• Yes, since there was a clear difference in cancer rates.

• Yes, as long as proper sampling techniques had been used when gathering the data.

• Yes, as long as there were no other obvious possible causes that could have confounded the results that were found.

• Yes, since there are clear explanatory and response variables.

• No.