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SOLUTIONS MANUAL for Stochastic Modeling: Analysis and ...

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125<br />

When we fix the initial state, the expectation of interest is<br />

E[̂θ | S 0 =1]<br />

a conditional expectation, only 1 term of (1).<br />

Remember that “expectation” is a mathematical averaging process over the possible<br />

outcomes. When we sample the initial state, all initial states are possible. When we<br />

fix the initial state, only 1 initial state is possible. There<strong>for</strong>e, the probability distribution<br />

of the estimator changes, even though the results of the simulation (outcome)<br />

may be the same.<br />

⎛ ⎞<br />

0.429<br />

⎜ ⎟<br />

19. π ≈ ⎝ 0.333 ⎠<br />

0.238<br />

There<strong>for</strong>e<br />

Pr{S =3} = π 3 ≈ 0.238<br />

E[S] = π 1 +2π 2 +3π 3 ≈ 1.809<br />

Var[S] =<br />

3∑<br />

(j − 1.809) 2 π j ≈ 0.630<br />

j=1<br />

A 1% relative error <strong>for</strong> Pr{S =3} implies that<br />

There<strong>for</strong>e, | 0.238 − p (n)<br />

13 |≤ 0.002.<br />

A 1% relative error <strong>for</strong> E[S] implies that<br />

| 0.238 − p (n)<br />

13 |<br />

≤ 0.01<br />

0.238<br />

| 1.809 − E[S n | S 0 =1]|<br />

1.809<br />

There<strong>for</strong>e, | 1.809 − E[S n | S 0 =1]|≤ 0.018 where<br />

≤ 0.01<br />

E[S n | S 0 =1]=<br />

3∑<br />

j=1<br />

jp (n)<br />

1j<br />

A 1% relative error <strong>for</strong> Var[S] implies that<br />

| 0.630 − Var[S n | S 0 =1]|<br />

0.063<br />

≤ 0.01

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