16.01.2013 Views

Journal of Computers - Academy Publisher

Journal of Computers - Academy Publisher

Journal of Computers - Academy Publisher

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

JOURNAL OF COMPUTERS, VOL. 6, NO. 9, SEPTEMBER 2011 1827<br />

level is determined by the p value <strong>of</strong> the statistic Z. If p < α ,<br />

0 H is denied; otherwise,<br />

Table 1: Moran’s I value <strong>of</strong> China’s manufacturing agglomeration (1999-2008)<br />

Year Moran’s I Mean<br />

Standard dev<br />

iation<br />

p value<br />

1999 0.3191 -0.0333 0.1073 0.0060<br />

2000 0.3216 -0.0330 0.1087 0.0058<br />

2001 0.3342 -0.0333 0.1072 0.0042<br />

2002 0.3063 -0.0337 0.1081 0.0062<br />

2003 0.3147 -0.0321 0.1094 0.0053<br />

2004 0.3294 -0.0337 0.1097 0.0042<br />

2005 0.3421 -0.0345 0.1112 0.0031<br />

2006 0.3572 -0.0335 0.1131 0.0031<br />

2007 0.3377 -0.0332 0.1100 0.0032<br />

2008 0.3496 -0.0324 0.1090 0.0032<br />

From table 1 we can make a conclusion that there was<br />

a significant positive spatial autocorrelation between<br />

China’s provincial manufacturing industries. This<br />

indicates that China's manufacturing industry did not<br />

distribute randomly, and the spatial distribution <strong>of</strong><br />

manufacturing industry showed a clear concentration<br />

trend over the last decade: the provinces that have similar<br />

LQ coefficient tend to concentrate geographically.<br />

III. METHOD AND MODEL<br />

A. Research Methods<br />

(a) Spatial Lag Model<br />

Spatial Lag Model (SLM) is mainly used to discuss<br />

whether there is a spillover effect <strong>of</strong> variables in a region.<br />

The model is expressed as follows:<br />

y = ρ Wy + Xβ<br />

+ ε<br />

In the formula above, y is a dependent variable;<br />

X is a n × k matrix <strong>of</strong> exogenous explanatory<br />

variables; ρ is a spatial regression coefficient, reflecting<br />

the effect <strong>of</strong> spatial dependence in observations; W is a<br />

n× n matrix <strong>of</strong> spatial weight;<br />

Wy<br />

is a spatial lagged<br />

dependent variable; ε is a random error vector.<br />

Parameter β reveals the effect the explanatory<br />

variable X has to dependent variable y . Spatial lagged<br />

dependent variable Wy is a exogenous variable<br />

reflecting how spatial distance influence the act <strong>of</strong><br />

regions. The act <strong>of</strong> regions is strongly affected by the<br />

cultural environment and the transfer cost related to<br />

spatial distance.<br />

(b) Spatial Error Model<br />

Spatial Error Model (SEM) is expressed as follows:<br />

y = Xβ<br />

+ ε,<br />

ε = λWε<br />

+ µ<br />

In the formula above, ε is a random error vector; λ<br />

is a n × 1 spatial error matrix <strong>of</strong> dependent variable<br />

vector; µ is a random error vector in normal<br />

distribution.<br />

Parameter β reveals the effect the explanatory<br />

variable X has to dependent variable y . Parameter λ<br />

© 2011 ACADEMY PUBLISHER<br />

0 H is accepted.<br />

reflects the effect <strong>of</strong> spatial dependence in observations.<br />

The spatial dependence in random error term measures<br />

how the error impact <strong>of</strong> dependent variable <strong>of</strong><br />

neighboring areas influence the observations in this<br />

region.<br />

(c) Estimation method<br />

Considering the endogeneity <strong>of</strong> explanatory variables<br />

in spatial regression model, coefficient estimates will be<br />

biased or invalid if we use OLS method to estimate the<br />

coefficient in Spatial Lag Model and Spatial Error Model.<br />

Instead, we can use other methods to estimate, such as<br />

Instrumental Variable method, Maximum Likelihood<br />

method, Generalized Least Squares method and<br />

Generalized Method <strong>of</strong> Moments. Anselin (1998)<br />

recommended Maximum Likelihood method for<br />

estimating the coefficient in SLM and SEM.<br />

(d) ( A 5)<br />

choice between SLM, SEM and spatial<br />

autocorrelation test<br />

Anselin and Florax (1995) proposed the following<br />

criterion: We can determine that Spatial Lag Model<br />

would be more appropriate if (a) LMLAG is more<br />

significant than LMERR statistically; (b) R-LMLAG is<br />

significant but R-LMERR is not significant. In the<br />

Opposite, Spatial Error Model would be better if (a)<br />

LMERR is more significant than LMLAG; (b)<br />

R-LMERR is significant but R-LMLAG isn’t.<br />

Besides R-squared, some common criterion includes<br />

Log likelihood, Likelihood Ratio, Akaike Information<br />

Criterion (AIC) and Schwartz Criterion (SC). The higher<br />

the Log likelihood, the lower the AIC and SC, the<br />

better the model. These indicators can also be used to<br />

compare the regression effect between OLS, SLM and<br />

SEM.<br />

B. Econometric Model<br />

In this ( article, 6)<br />

we proposes the main factors that<br />

affecting industrial agglomeration from four perspectives:<br />

comparative advantage, new economic geography,<br />

knowledge spillovers and the role <strong>of</strong> government.<br />

Considering measurability <strong>of</strong> indicators and availability<br />

<strong>of</strong> data, we proposes the following twelve indicators in<br />

table 2.

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!