6.2.2 Econometric Model...............................
In this section, we would build econometric model to explore the factors impacting
on the university research efficiency and their magnitudes. More specifically, the
efficiency scores computed by DEA are set as dependent variable, and the factors
which are supposed be the influencing factors are set as independent variables.
Since this process of analysis can be clearly divided into two steps, Coelli ( 1998 )
named this process as two-stage DEA approach.
As DEA efficiency scores are continuous data valued between 0 and 1, truncated
from both sides, the dependent variable in the regression equations will be valid
only on the interval of (0,1]. Thus, it is not suitable to use OLS model to carry out
our analysis. To overcome this barrier, an alternative is to use Tobit model in the
second stage. Tobit model wasfirst proposed by Nobel Laureate James Tobin in
1958, andfirst employed by economist Goldberger in 1964, and then further
developed by other economists over decades. Tobit is a kind of model with limited
dependent variable, it’s frequently used when the dependent variable is a truncated
value or censored value, which is a popular parametric method.
A standard form of Tobit model is as below:
yi¼b 0 þ
Xk
j¼ 1bXijþei
yi¼yi;yi2ð 0 ; 1 Þ
yi¼ 0 ;yi2ð1; 0 Þ
yi¼ 1 ;y
i2ð^1 ;þ1Þð 6 : 1 Þ
In Eq. (6.1), yi is a latent dependent variable, satisfying all the classic
assumptions of linear model.yiis the observed dependent variable,Xijis vector of
independent variables,bis vector of partial coefficients, eiis independent and
satisfyingeiNð 0 ;rÞ.
There are numerous empirical studies applying two-stage DEA approach to
analyze questions of efficiency and their influencing factors. As early as 1998,
Kirjavainen and Loikkanent ( 1998 ) used this method to analyze and compare the
differences and causes of senior high schools’efficiency in Finland. Watcharasriroj
and Tang ( 2004 ) applied this method to analyze the efficiency of 92 non-profit
public hospitals. In China, this method has been applied to analyze and evaluate
efficiency of bank industries and agriculture industries. For instance, in the study of
Wang ( 2003 ), Tobit model was applied to analyze the innovation efficiency of
high-tech zones in China, and this study found that factors including innovation
capacity, economic strength, social contribution, location advantage, and interna-
tionalization all have impacts on efficiency. In existing literature, wefind there are
few empirical studies which analyze factors impacting university research efficiency
with Tobit method. In this chapter, we will try to apply this approach to analyze the
influencing factors of research efficiency of 211Us, and expect this would bring us
276 6 Exploring Factors Impacting on Research Efficiency...