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Explanation:
For a 98% VaR model over days, the expected number of exceptions is . To determine if the model is poorly calibrated at a 95% confidence level (two-tailed Kupiec POF test), we approximate using the normal distribution:
The standard deviation is .
The critical Z-value for a 95% two-tailed test is $1.96x = 5.04 + 1.96 \times 2.222 \approx 9.39$.
Since exceptions must be whole integers, 10 or more exceptions fall firmly into the rejection region (). Therefore, 10 daily losses would lead Roy to conclude the model is incorrectly calibrated (rejecting the null hypothesis).
Q.21 Michael Roy, a risk analyst at a large multinational bank, is backtesting the VaR model of the bank. The model being tested is a daily, 98% VaR model. If the backtest is conducted for one year at the 95% confidence level, and assuming 252 days in a year, what is the number of daily losses that will lead Roy to conclude that the model is not calibrated correctly?
A
8
B
9
C
10
D
5
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