Financial Risk Manager Part 1

Financial Risk Manager Part 1

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Assume the shock in a time series is approximated by Gaussian white noise. Yesterday's realization, y(t−1)y_{(t-1)} was 0.015 and the lagged shock was -0.160. Today's shock is 0.170. If the weight parameter theta, θ\theta, is equal to 0.70, determine today's realization under a first-order moving average, MA(1), process._

TTanishq



Explanation:

Explanation

For an MA(1) process, the general form is:

yt=μ+ϵt+θϵt−1y_t = \mu + \epsilon_t + \theta \epsilon_{t-1}

Where:

  • yty_t is today's realization
  • μ\mu is the mean (assumed to be 0 for white noise)
  • ϵt\epsilon_t is today's shock (0.170)
  • ϵt−1\epsilon_{t-1} is the lagged shock (-0.160)
  • θ\theta is the weight parameter (0.70)

Plugging in the values:

yt=0+0.170+(0.70)(−0.160)y_t = 0 + 0.170 + (0.70)(-0.160) yt=0.170−0.112y_t = 0.170 - 0.112 yt=0.058y_t = 0.058

Wait, let me recalculate this carefully:

yt=ϵt+θϵt−1y_t = \epsilon_t + \theta \epsilon_{t-1} yt=0.170+(0.70)(−0.160)y_t = 0.170 + (0.70)(-0.160) yt=0.170−0.112y_t = 0.170 - 0.112 yt=0.058y_t = 0.058

However, looking at the options, 0.058 corresponds to option D, not option B (0.075). Let me double-check the calculation:

  • Today's shock: 0.170
  • Lagged shock: -0.160
  • Theta: 0.70
  • Product: 0.70 × (-0.160) = -0.112
  • Sum: 0.170 + (-0.112) = 0.058

The calculation gives 0.058, which matches option D. But let me verify if there's any additional information I might be missing.

Actually, in an MA(1) process, yesterday's realization y(t−1)y_{(t-1)} is not directly used in calculating today's realization. The MA(1) process only depends on current and lagged shocks. Therefore, the correct calculation is:

yt=ϵt+θϵt−1=0.170+0.70×(−0.160)=0.170−0.112=0.058y_t = \epsilon_t + \theta \epsilon_{t-1} = 0.170 + 0.70 \times (-0.160) = 0.170 - 0.112 = 0.058

Therefore, the correct answer is D (0.058).

The confusion might be that yesterday's realization (0.015) was given but is not needed for the MA(1) calculation. The MA(1) process depends only on current and lagged shocks, not on previous realizations._

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