4.2 Observation or Experiment

Determine which brands of orange juice people prefer. The people are randomly chosen at the supermarket and are asked to taste both brands without knowing which brand they are drinking.

• Experiment
• Observational Study

Determine if people who take vitamin C every day are less likely to get colds.

• Experiment
• Observational Study

Compare the grades on a final math test of 25 students who use calculators and 25 students who do not use calculators. The students decide which group they are in.

• Experiment
• Observational Study

A teacher asks her students to write down all they eat in a day and then calculate the total number of calories consumed. 

• Experiment
• Observational Study

The cafeteria manager of a high school wants to find out if high prices are keeping students from using the cafeteria. Fifty students are chosen at random to receive half-price lunch passes every day for a month. The manager then records the number of passes used. 

• Experiment
• Observational Study

Of observational studies, surveys, and experiments, random sampling is only important in experiments.

• True
• False

If you discovered that eating granola for breakfast improved English scores in a random sample of 20 males from your school, it would not be valid to generalize these results to the females.

• True
• False

When one examines the entire population instead of a subgroup of the population, this is called a ____________.

• Sampling
• Census
• Bias

To find out what the preferred ice cream flavor is, wait outside an ice cream parlor and ask every 4th person leaving the store to name his or her favorite flavor until you get 25 responses is an example of...

• Convenience Sample
• Simple Random Sample
• Stratified Random Sample
• Systematic Sample

To study the amount of time students spend doing homework each day, use a random number generator to select 25 students from the student enrollment database to survey.

• Convenience Sample

• Simple Random Sample

• Stratified Random Sample