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The following sample autocorrelation estimates have been obtained using 200 data points:
| Lag | 1 | 2 | 3 | 4 |
|---|---|---|---|---|
| Coefficient | 0.15 | -0.14 | -0.1 | -0.08 |
What is the value of the Box-Pierce Q-statistic?
A
1.05
B
17.1
C
11.7
D
12.5
Explanation:
Explanation:
The Box-Pierce Q-statistic is calculated using the formula:
Where:
Step-by-step calculation:
Square each autocorrelation coefficient:
Sum the squared coefficients: 0.0225 + 0.0196 + 0.01 + 0.0064 = 0.0585
Multiply by sample size T: 200 × 0.0585 = 11.7
Therefore, the Box-Pierce Q-statistic is 11.7, which corresponds to option C.
Note: The Box-Pierce Q-statistic tests whether a group of autocorrelations of a time series are different from zero. It is approximately distributed as a chi-square distribution with m degrees of freedom under the null hypothesis of no autocorrelation.