205
Hội thảo Khoa học Quốc tế
...
ISO 14001 during the period study is used as the proxy variable to measure vertical green product
diversification (VGPD), and the certification status of eco-label as the proxy variable to measure
horizontal green product diversification (HGPD).
3.2.2. Independent variables
Regulations
Some researchers use a single variable as the proxy for measuring regulatory stringency,
such as waste gas emissions data (Prakash and Potoski, 2007; Madsen, 2009; He, 2010), and
the environmental-related investments (Kassinis and Vafeas, 2006). Some critics argue that single
variable criterion, such as SO2emissions, may only reflect the environmental policy in a narrow
category rather than the overall stringency of environmental regulations (Xing and Kolstad, 2002).
Cagatay and Mihci (2006) constructed a composite index for environmental stringency calculated
from multiple variables, such as expenditures on pollution abatement as a percentage of GDP,
wastewater treatment as a percentage of population served, treatment and disposal of hazardous
waste as a percentage of generated hazardous waste, etc. In this study, we use a composite index
named as Environmental Management Index (EMI) as the proxy of regulatory stringency in each
province which scales the following five sub-indices, namely, (1) the implementation state of
environmental impact assessment; (2) regime of three concurrences in environmental protection; (3)
environmental government employees per thousand persons; (4) the handling rate of environmental
complaint letters; and (5) the handling rate of environmental complaint visit. The EMI values
of each province are issued by the National Statistical Indicators System (NSIS) of the General
Statistics Office (GSO) provides coordination for data collection between provinces and the
national government,. The index data come from the Report Study for a Provincial Environmental
Performance Index in Vietnam. We argue that the larger the index value of a province, the stricter
the environmental regulations in that province will be.
Customers
In this paper, we employ the variable-EXPORT to measure the effect of foreign customers
on horizontal and vertical green product diversification of SMEs. The variable of export status
(EXPORT) measures whether the focal firms have sold their products to foreign markets during
2010–2014. The variable EXPORT takes a value « 1 » if the firm exports in a given year and « 0 »
otherwise.
Entrepreneur
Entrepreneur (ENT) has an important role in defining the environmental orientation of the
firm and strategic decision making ( ). A dummy variable that takes the value « 1 » when the
firm indicates that environmental practices were developed because they were part of the company
values, mission, image and other avantage and « 0 » otherwise.
Community
We use per capital income (GDPPC) in each province as the proxy for the community
stakeholders’ pressure in that province. This proxy captures the heterogeneous capacity of community
stakeholders in influencing the adoption of horizontal and vertical green product diversification
practices. Data of per capita income was collected from the Vietnam Statistics Yearbook. The
variable of GDPPC is calculated using each province’s GDP and the total number of population,
both coming from the Vietnam Statistic Yearbooks in 2010 to 2014.
Foreign investors
The presence of foreign investment is measured by the dummy variable (FDI = 1 represents the
presence of FDI from non-vietnamese western countries).
