Lab 4#

Part 1#

Write a .do file which imports transplants.dta and performs the data management/exploratory data analysis tasks described below using the slides we have discussed in class. Your .do file (lab4_lastname.do) and must create a log file (lab4_lastname.log). This file will contain your answers for both part 1 and part 2 of today’s lab. Your .do file should follow conventions for .do file structure described in class. Do not submit your log files as part of the assignment.

  1. Create a new variable called ctr_volume that contains the transplant center volume (total number of transplants performed in each transplant center). The transplant center can be identified by ctr_id.

  2. Use summarize, detail to show the distribution of ctr_volume. For question 2, you should analyze one observation per center, not one observation per transplant recipient. (Hint: Tagging can help with this)

  3. Generate a variable called unknown which is a 1 for all patients whose cause of end-stage renal disease (ESRD) is unknown/uncertain/blank (extended_dgn = “ESRD UNKNOWN ETIOLOGY”, “ESRD OF UNCERTAIN ETIOLOGY”, etc.) and a zero for all other patients. Display the following sentence:

xxx of 2000 patients (yy.y%) have an unknown cause of ESRD.

Except fill in the correct numbers.

  1. How many patients died within six months of their transplant (died==1 and transplant date falls ≤ 180 days before end date)? Display the following sentence:

xxx of 2000 patients (yy.y%) died within 6 months of their transplant date.

Except fill in the correct numbers.

  1. For each blood type, what is the mean waiting time for a transplant? (variable: wait_yrs) What is the median waiting time for a transplant? Use egen, tagging, and list to display the blood type, mean wait time, and median wait time of each blood type so that only one record is displayed per blood type.

Lab 4 Part 2

  1. Create a variable called over50 which is a 1 for any recipient age >50 and 0 for everyone else. Draw a survival curve stratified by over50.

  2. Is the difference in post-transplant survival by over50 statistically significant (p>0.05)? Write one of the following sentences:

There is a statistically significant difference in survival by age category (p<0.05)

or

There is no statistically significant difference in survival by age category (p=0.x)

  1. Run a Cox regression on over50 (command stcox over50). Print this sentence:

Hazard ratio: x.xx (95% CI y.yy-z.zz)

Except fill in the correct values.