A study was conducted in males who underwent prostatectomy for treatment of prostate cancer. A prostatectomy is a surgical procedure for the partial or complete removal of the prostate.

Data from 316 participants have been saved in the Datasets section of the course Sharepoint page as:

Assessment data > Quizzes > Quiz 1 > prostate.rds

The datasets contain the following variables:

• age: participant age (years)
• size: the size of the participant’s prostate (grams)

• preop_psa: preoperative

  prostate specific antigen (PSA) (ng/mL)

• time_to_recurrence: time to recurrence of prostate cancer, or

  withdrawal from the study, whichever came first (months)

Calculate the median and interquartile range time to recurrence.