**Question 1) ****Person 1 has hazard hi(t) = 1, and Person 2 has hazard h2(t) = 2. What is the probability of dying within the first year for each patient?**

**The survival function S(t) in terms of the hazard function is:**

*Hint:***0.63, 0.86**

- 0.5, 0.6

- 0.37, 0.14

**Question 2) Let T >0.**

**For patient 1, let the survival function be Si(t) and the hazard function be hi(t).**

**For patient 2, let the survival function be S2(t) and the hazard function be h2(t)**

You see that S(T) > S2(T). The survival probability of patient 1 at time T is higher than the survival probability of patient 2 at time T.

**Which of the following is true about the hazard of patient 1 and 2 at time T?**

*Hint:*- h_1(T)>h_217)
- h_1(1) <h_2(1)
- h_1(T) = h_2(1)
**None of the above**

**Question 3)**

**Now assume that the hazards for patient 1, hy and for patient 2. h2 are proportional to each other. Also assume that Si(T) > S2(T) for some T>0.**

Then which of the following is true about the hazards?

- h_1(1) = h_201)
**h_1(1)<h_2(1)**- h_1(T)>h_2(1)

**Question 4)**

**You've fit a Cox model on 2 features: age and smoking status.**

**0.36**- 2.64
- 2.7

**Question 5)**

**You've fit a cox model and have the following coefficients:**

Which of the following interpretations is most correct?

- All other things held equal, having lower age increases your risk
- All other things held equal, having higher BP decreases your risk
**All other things held equal, being a female decreases your risk**

**Question 6)**

**Assume h_1(t) = t, and h_2(t) = 1.0. At which time T> 0 does 5_1(T) = 5_2(T)?**

**2**- 1
- 0.5
- None of the above

**Question 7)**

**Using the Nelson-Aalen estimator estimate H(7), the value of the cumulative hazard at t=7 for this dataset.**

The Nelson-Aalen estimator is:

**7/12**- 8/11
- 519

**Question 8)**

**Which risk assignments would make this pair concordant?**

- 0.3, 0.8
- 0.5, 0.3
- 0.5, 0.5
**The pair is not permissible**

**Question 9)**

**Compute the Harrell C-index for the following dataset and risk scores:**

Step 1: Find all the permissible pairs

Step 2: of the permissible pairs, determine which ones are concordant.

Step 3: of the permissible pairs, determine which ones are risk ties.

- 1.0
**0.8**- 0.7

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