If someone can answer this using STATA software. I PROSTATE CANCER AMONG BLACK AND WHITE MEN. A retrospective cohort

study was designed and implemented to gather data on all cases of adenocarcinoma of the prostate

diagnosed among Black and White men at two Department of Veterans Affairs hospitals and two

private university medical centers between January 1, 1986, and December 31, 1990.

Researchers were interested in investigating the association between mortality rate and cancer stage,

locstg (localized and regional, versus distant), differentiation, grpdiff (well, moderate, poor), age at

diagnosis, dxage, and comorbidity score, charlson, as well as race/ethnicity, black(1=black, 0=white).

In addition, time from diagnosis to death or last follow-up(futimeyr) among Black and White patients

were compared. A reduced data set from this study is saved under ProstateCa Mortality.dta.

1. Explore the association between age at diagnosis (hint: use agegrp, 45-64;65-74;75+) and survival.

Is the observed behavior expected? Why?

2. Compute the death rate among patients with localized/regional and compare with the correspon-

ding rate among patients diagnosed with distant disease. Is the rate ratio statistically signicant?

3. Plot the Kaplan-Meier curves by staging of prostate cancer. Are the survival distributions for

patients with localized/regional and distant statistically different?

4. Plot the Kaplan-Meier curves by race/ethnicity. Who experiences worse survival? Are the diffe-

rences statistically signicant?

5. State the Cox Proportional hazards model to investigate the association between race/ethnicity

and mortality adjusting for cancer stage, cancer differentiation, and age at diagnosis.

6. Fit a multivariate Cox Proportional hazards regression model to investigate the association be-

tween race/ethnicity and mortality adjusting for cancer stage, cancer differentiation, and age at

diagnosis.

7. Does comorbidity score (charlson) confound the association between mortality and race/ethnicity?

8. Re-do 7(above) using groups variables (agegrp) and (scrgrp). Interpret all the parameters in the

model.

9. Is comorbidity score (scrgrp) an effect modier of the association between race/ethnicity and

mortality?

10. What is your nal model? Interpret the model parameters and explain your ndings.

11. Perform a graphical assessment of the nal Cox-PH model for each of the independent variables.