options: Develop understanding of statistical variability.

Make inferences and justify conclusions from sample surveys, experiments, and observational studies.

Investigate chance processes and develop, use, and evaluate probability models.

Draw informal comparative inferences about two populations.

Use random sampling to draw inferences about a population.

Summarize, represent, and interpret data on two categorical and quantitative variables.

Summarize, represent, and interpret data on a single count or measurement variable.

Use the rules of probability to compute probabilities of compound events in a uniform probability model.

Use probability to evaluate outcomes of decisions.

Understand independence and conditional probability and use them to interpret data.

Interpret linear models.

Understand and evaluate random processes underlying statistical experiments.

Investigate patterns of association in bivariate data.

Calculate expected values and use them to solve problems.

Summarize and describe distributions.
problem_activity: Task
A student interested in comparing the effect of different types of music on short-term memory conducted the following study:  80 volunteers were randomly assigned to one of two groups.  The first group was given five minutes to memorize a list of words while listening to rap music.  The second group was given the same task while listening to classical music.  The number of words correctly recalled by each individual was then measured, and the results for the two groups were compared.
Is this an experiment or an observational study?  Justify your answer.
In the context of this study, explain why it is important that the subjects were randomly assigned to the two experimental groups (rap music and classical music).


correct_option_index: 1