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"Frontmatter". In: Analysis of Financial Time Series

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316 VECTOR TIME SERIESTable 8.3. Order-Specification Statistics for the Monthly LogReturns <strong>of</strong> IBM Stock and the S&P 500 <strong>In</strong>dex from January1926 to December 1999. The 5% and 1% Critical Values <strong>of</strong>a chi-Squared Distribution with 4 Degrees <strong>of</strong> Freedom are 9.5and 13.3.Order 1 2 3 4 5 6M(i) 9.81 8.93 12.57 6.08 9.56 2.80AIC 6.757 6.756 6.750 6.753 6.751 6.756statistics are nonsignificant at the 1% level, confirming the previous observation thatthe dynamic linear dependence between the two return series is weak.Estimation and Model CheckingFor a specified VAR model, one can estimate the parameters using either the ordinaryleast squares method or the maximum likelihood method. The two methodsare asymptotically equivalent. Under some regularity conditions, the estimates areasymptotically normal; see Reinsel (1993). A fitted model should then be checkedcarefully for any possible inadequacy. The Q k (m) statistic can be applied to theresidual series to check the assumption that there are no serial or cross-correlationsin the residuals. For a fitted VAR(p) model, the Q k (m) statistic <strong>of</strong> the residuals isasymptotically a chi-squared distribution with k 2 m − g degrees <strong>of</strong> freedom, where gis the number <strong>of</strong> estimated parameters in the AR coefficient matrixes.Example 8.4. (continued) Table 8.4(a) shows the estimation results <strong>of</strong> aVAR(3) model for the bivariate series <strong>of</strong> monthly log returns <strong>of</strong> IBM stock andTable 8.4. Estimation Results <strong>of</strong> a VAR(3) Model for the Monthly Log Returns, in Percentages,<strong>of</strong> IBM Stock and the S&P 500 <strong>In</strong>dex from January 1926 to December 1999.Param. φ 0 Φ 1 Φ 3 Σ(a) Full modelEstimate1.200.580.011 0.108−0.013 0.0840.039 −0.112−0.007 −0.10544.44 23.5123.51 31.29St. Error0.230.190.043 0.0510.036 0.0430.044 0.0520.037 0.044(b) Simplified modelEstimate1.240.570 0.1170 0.0730 −0.0830 −0.10944.48 23.5123.51 31.29St. Error0.230.19− 0.040− 0.033− 0.040− 0.033

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