As a member of the quality improvement committee, a nurse is evaluating the results of recently implemented measures designed to reduce medication errors. Which of the following methods should the nurse use to evaluate the success of the changes?

Conduct a study about the time and money costs of implementing the change.

Provide the staff with a questionnaire to quantify staff satisfaction with the changes.

Compare the number of medication errors before and after the action was implemented.

Establish a benchmark to identify a standard of performance.