ST 762, HOMEWORK 1 SOLUTIONS, FALL 2007
1. (a) Here is the plot, with the observation connected by a dashed line.
0.0 0.5 1.0 1.5 2.0
1 2 3 4
days
viral load/10^6
(b) See the two Rprograms and their output; they are fairly well-documented, so you should
be able to follow them even if you do not know R. The programs use analytic derivatives.
Note that, as expected, both algorithms lead to the same solutions for each θ.
(c) The viral load for this patient at time 0 is estimated to be exp(1.425401)×106= 4159525.2
copies RNA per ml. It is critical that, whenever you report an estimate of anything, you
provide the associated units!
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