1.A Cox proportional hazards model is estimated relating time to psychiatric hospitalization in patients with severe mental illness. The risk factors include age, sex, prior hospitalization for mental illness, and an indicator of bipolar disorder. The parameter estimates and significance levels for the model are shown here. Which of the predictors are statistically significantly associated with time to psychiatric hospitalization?

Predictor Parameter Estimate p-value

Age, years 0.0045 0.5647

Sex (0=female, 1=male) -0.4841 0.0341

Prior hospitalization 0.3726 0.6178

(0=no, 1=yes)

Bipolar disorder 0.7561 0.0042

(0=no, 1=yes)

A) Sex & Bipolar disorder

B) Sex & Age

C) Prior hospitalization & Bipolar disorder

D) None of Above

True or False? One of the most popular regression techniques for survival analysis is Cox proportional hazards regression. Cox proportional hazards regression is used to relate several risk factors or exposures, considered simultaneously, to survival time.

True or False? Greenwood's formula allows one to calculate the standard error of the survival estimates for a particular study.