38
provided ecological information, the variable is set to 1. The dummy variable of
information provision was incorporated as a cross-term with other attributes except
for Tour Fee (i.e., Carp Removal option, Pick-up option, Tour Time and Tour Time
2
).
By following existing literature in applied economics, preference for the Tour Fee
(i.e., money) was supposed not to be affected by the information (e.g., Das et al.
2009; Hole and Kolstad 2012; Layton and Brown 2000; Morey and Rossmann
2003; Revelt and Train 1998; Scarpa et al. 2008). The ASC variable was set to 1 if
respondents chose not to attend the canoe tour (i.e., selected choice 3 in choice set),
and the ASC variable was set to 0 if respondents selected to attend the canoe tour
(i.e., selected choice 1 or 2 in choice set). This model needed to make assumptions
about the distributional form of the coefficients of each attribute. Except for Tour
Fee, all variables were assumed to be normally distributed.
In addition, the marginal willingness to pay (MWTP) is able to be calculated by
using the estimates for each coefficient as following equation (Haab and
McConnell 2003):
MWTP
attribute
Tour Fee
=
β
β
(3.6)
Note that the WTP for both Carp Removal option and Pick-up option attributes
was calculated by doubling the MWTP since the attributes were effect-coded
(Louviere et al. 2000).
3.3 Results
Table 3.2 presents the estimated results of the RPL model. We applied the effect
code to the dummy variables concerning Carp Removal option and Pick-up option.
Thus, the relative values of coefficient are important instead of the absolute values.
Table 3.2 shows the mean of coefficients, standard deviations of the random coefficients, and the effect of ecological information on each random parameter variables in the RPL models, with their standard errors. The standard deviations for
each of the random coefficients indicate the heterogeneity of individual preferences
relative to the preference of the population.
Table 3.2 indicates that the mean of the Carp Removal option coefficient is significantly negative (Coefficient = −0.366; SE = 0.131) at the 99.9% level: Carp
Removal option decreased the probability of choosing canoe tours. However, standard deviations for Carp Removal option are also statistically significant: there is
preference heterogeneity for Carp Removal option (Fig. 3.3). The mean of the
respondents’ WTP for Carp Removal option was −988 JPY (100 JPY = about 0.9
USD and 0.8 EURO in November 2019). The other variables’ coefficients are also
significant at over 95% levels, except for ASC. The coefficient of Pick-up option
K. Mameno et al.
provided ecological information, the variable is set to 1. The dummy variable of
information provision was incorporated as a cross-term with other attributes except
for Tour Fee (i.e., Carp Removal option, Pick-up option, Tour Time and Tour Time
2
).
By following existing literature in applied economics, preference for the Tour Fee
(i.e., money) was supposed not to be affected by the information (e.g., Das et al.
2009; Hole and Kolstad 2012; Layton and Brown 2000; Morey and Rossmann
2003; Revelt and Train 1998; Scarpa et al. 2008). The ASC variable was set to 1 if
respondents chose not to attend the canoe tour (i.e., selected choice 3 in choice set),
and the ASC variable was set to 0 if respondents selected to attend the canoe tour
(i.e., selected choice 1 or 2 in choice set). This model needed to make assumptions
about the distributional form of the coefficients of each attribute. Except for Tour
Fee, all variables were assumed to be normally distributed.
In addition, the marginal willingness to pay (MWTP) is able to be calculated by
using the estimates for each coefficient as following equation (Haab and
McConnell 2003):
MWTP
attribute
Tour Fee
=
β
β
(3.6)
Note that the WTP for both Carp Removal option and Pick-up option attributes
was calculated by doubling the MWTP since the attributes were effect-coded
(Louviere et al. 2000).
3.3 Results
Table 3.2 presents the estimated results of the RPL model. We applied the effect
code to the dummy variables concerning Carp Removal option and Pick-up option.
Thus, the relative values of coefficient are important instead of the absolute values.
Table 3.2 shows the mean of coefficients, standard deviations of the random coefficients, and the effect of ecological information on each random parameter variables in the RPL models, with their standard errors. The standard deviations for
each of the random coefficients indicate the heterogeneity of individual preferences
relative to the preference of the population.
Table 3.2 indicates that the mean of the Carp Removal option coefficient is significantly negative (Coefficient = −0.366; SE = 0.131) at the 99.9% level: Carp
Removal option decreased the probability of choosing canoe tours. However, standard deviations for Carp Removal option are also statistically significant: there is
preference heterogeneity for Carp Removal option (Fig. 3.3). The mean of the
respondents’ WTP for Carp Removal option was −988 JPY (100 JPY = about 0.9
USD and 0.8 EURO in November 2019). The other variables’ coefficients are also
significant at over 95% levels, except for ASC. The coefficient of Pick-up option
K. Mameno et al.