Economic Models - Convex Optimization

Economic Models - Convex Optimization Economic Models - Convex Optimization

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A Novel Method of Estimation Under Co-Integration 31 It is obvious from these findings, the super consistency of the OLS. However, the method we introduce here, produces almost minimum variance errors, which is a quite desirable property, as suggested by Engle and Granger (Dickey et al., 1994, p. 27). Hence, we will mainly focus on this property in our next section. 6. Case Study 2: Further Evidence Regarding the Minimum Variance Property With the same set of data, the co-integration vector without an intercept obtained by applying the ML method is: 1 − 0.9422994 − 0.058564 The errors corresponding to this vector are obtained from: û i = C i − 0.9422994I i − 0.058564W i (18) Again these errors will be denoted by uml i . Next, we apply SVD to in Eq. (12) to obtain matrix C, which is: ⎡ ⎤ 1 −0.9192042 −0.066081211 ⎢ ⎥ C = ⎣ 1 1.160720 −1.012970 ⎦ 1 0.9395341 2.063768 and ⎛ ⎞ 1.359891 ⎜ ⎟ Euclidean norm = ⎝ 1.836676 ⎠ 2.47828 The singular values of are: f 1 = 0.89514, f 2 = 0.0403121 and f 3 = 0.0026218249 Again, all f i ’s are less than 1. We consider the first row of C, so that the errors corresponding to this vector are obtained from: û i = C i − 0.9192042I i − 0.066081211W i (19) These errors will be also denoted by usvd i . The co-integrating vector reported by the authors (p. 109), which is obtained from the VAR(2), including the dummies mentioned previously,

32 Alexis Lazaridis by applying the ML procedure is given by: 1 − 0.93638 − 0.03804 and the errors obtained from this vector are computed from: û i = C i − 0.93638I i − 0.03804W i (20) As in the previous case, these errors will be denoted by ubook i . The minimum variance property can be seen from the following: Standard deviation of Standard deviation of Standard deviation of {uml i } {usvd i } {book i } 0.0169 0.0166 0.0193 Next, we consider the model presented by Banerjee et al. (1993, pp. 292–293) that refers to VAR(2) with constant dummy and trend. The state vector x ∈ E 4 consists of the variables (m − p), p, y, and R. The data (in logs) are presented in Harris (1995, statistical appendix, pp. 153– 155. Note that the entries for 1967:1 and 1973:2 have to be corrected from 0.076195 and 0.56569498 to 9.076195 and 9.56569498, respectively). Considering the co-integration vector reported by the authors, which has been obtained by applying the ML method, we compute the errors from: û i = (m − p) i + 6.3966p i − 0.8938y i + 7.6838R i . (21) These errors will be denoted by uml i . Estimating the same VAR by OLS, we get, ⎡ ⎤ −0.089584 0.16375 −0.184282 −0.933878 −0.012116 −0.9605 0.229635 0.206963 = ⎢ ⎥ ⎣ 0.021703 0.676612 −0.476152 0.447157 ⎦ , −0.006877 0.118891 0.048932 −0.076414 ⎡ ⎤ ⎡ ⎤ 3.129631 0.001867 −2.46328 δ = ⎢ ⎥ ⎣ 5.181506 ⎦ and µ = −0.001442 ⎢ ⎥ ⎣ 0.003078 ⎦ −0.470803 −0.000366

32 Alexis Lazaridis<br />

by applying the ML procedure is given by:<br />

1 − 0.93638 − 0.03804<br />

and the errors obtained from this vector are computed from:<br />

û i = C i − 0.93638I i − 0.03804W i (20)<br />

As in the previous case, these errors will be denoted by ubook i .<br />

The minimum variance property can be seen from the following:<br />

Standard deviation of Standard deviation of Standard deviation of<br />

{uml i } {usvd i } {book i }<br />

0.0169 0.0166 0.0193<br />

Next, we consider the model presented by Banerjee et al. (1993,<br />

pp. 292–293) that refers to VAR(2) with constant dummy and trend. The<br />

state vector x ∈ E 4 consists of the variables (m − p), p, y, and R. The<br />

data (in logs) are presented in Harris (1995, statistical appendix, pp. 153–<br />

155. Note that the entries for 1967:1 and 1973:2 have to be corrected from<br />

0.076195 and 0.56569498 to 9.076195 and 9.56569498, respectively). Considering<br />

the co-integration vector reported by the authors, which has been<br />

obtained by applying the ML method, we compute the errors from:<br />

û i = (m − p) i + 6.3966p i − 0.8938y i + 7.6838R i . (21)<br />

These errors will be denoted by uml i .<br />

Estimating the same VAR by OLS, we get,<br />

⎡<br />

⎤<br />

−0.089584 0.16375 −0.184282 −0.933878<br />

−0.012116 −0.9605 0.229635 0.206963<br />

= ⎢<br />

⎥<br />

⎣ 0.021703 0.676612 −0.476152 0.447157 ⎦ ,<br />

−0.006877 0.118891 0.048932 −0.076414<br />

⎡ ⎤<br />

⎡ ⎤<br />

3.129631<br />

0.001867<br />

−2.46328<br />

δ = ⎢ ⎥<br />

⎣ 5.181506 ⎦ and µ =<br />

−0.001442<br />

⎢ ⎥<br />

⎣ 0.003078 ⎦<br />

−0.470803<br />

−0.000366

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