(e) Give interpretations for each HR for the model fitted in (c).
(f) Is the effect of age linear? Support your response empirically by fitting an appro-
priate main effects model and providing the appropriate plot.
1

2. An investigator wishes to combine her prior knowledge of anemia with the
first
Cox model (i.e., the
main effects model
) you fitted in Q1.
(a) Suppose that it is known that
S
(14) = 0
.
95 for a subject age 30. If possible, under
the assumed model, determine what
S
(14) would equal if that same subject was
actually age 40? If not possible, state what information you are missing.
(b) Suppose that it is known that
S
(28) = 0
.
90 for a subject age 25.
If possible,
under the assumed model, determine
S
(56) if that same subject was actually age
50. If not possible, state what information you are missing.
3. End-stage renal disease (ESRD; also referred to as ‘renal failure’) is increasing in
many countries worldwide, including the United States and Canada. Due to the

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- Fall '08
- Schaubel
- zi, LAF