options: Use data from a sample survey to estimate a population mean or proportion; develop a margin of error through the use of simulation models for random sampling.

Evaluate reports based on data.

Use data from a randomized experiment to compare two treatments; use simulations to decide if differences between parameters are significant.

Recognize the purposes of and differences among sample surveys, experiments, and observational studies; explain how randomization relates to each.
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: 3