  This paper extends the findings of Liu et al. (2015, Strategic environmental
corporate social responsibility in a differentiated duopoly market, Economics
Letters), along two dimensions. First, we consider the case of endogenous
market structure a la Vives and Singh (1984, Price and quantity competition in
a differentiated duopoly, The Rand Journal of Economics). Second, we refine the
ECSR certification standards in differentiated duopoly with rankings. We find
that optimal ECSR certification standards by NGO are the highest in Bertrand
competition, followed by mixed markets and the lowest in Cournot competition.
Next, NGO certifier will set the ECSR standards below the optimal level. Also,
we show that given the ECSR certification standards, there is a possibility of
both price and quantity contracts choices by the firms in endogenous market
structure.
