BIOS 280
                               Homework 3


1)
Fill-in the details for the efficiency calculations on pages 107,
last paragraph, starting at "Efron (1977)", and 108 of K&P.

2)
Interpret in detail models V and VI in stan06.sas.  (Hint:  Write and
sketch the contrast C(t) between two subjects.)

3)
Suppose that we have n0 observationsa with z=0 and n1 observations
with z=1 (n0, n1 > 1); i.e. a two-sample problem.
Suppose that there is no censoring and no ties.
Consider a proportional-hazards model,
                        h(.) = h0(.) exp(z beta).
Derive the score test statistic, from the partial likelihood, for
                   H0: beta = 0   vs   H1: beta <> 0.
Show that it is a linear rank statistic.