3
.
1
. Hypotheses The preceding discussion highlighted the impor-
tance of understanding the meaning of protest responses. An empirical model was presented as a
means for testing the following hypotheses: 1 protest beliefs are significantly associated with
attitude toward paying; 2 attitude toward paying is significantly associated with income and price;
and 3 attitude toward paying is significantly associated with WTP. These hypotheses corre-
spond to the following model parameters:
1. l
3,1
l
3,2
…l
3,6
not equal to 0. 2. g
1,3
g
2,3
not equal to 0. 3. b
3,4
not equal to 0. The structural equation model described earlier
can be compared across samples in order to test a fourth hypothesis: Attitude toward paying and its
relationships with other variables in the model are invariant with respect to variability in a range of
methodological factors. These methodological factors might include the type of payment vehicle,
the frequency of payments that households are required to pay, and the type of pollution abate-
ment intervention proposed.
If attitude toward paying is simply a reaction to mutable methodological conditions rather than to
the act of paying, it should vary in the presence of different payment vehicles, payment regimes, in-
terventions, etc. The same attitude toward paying that is expressed in reaction to one type of CV
survey would not manifest in the same form when different methodological characteristics apply. If
attitude toward paying is dependent upon such methodological characteristics then variations in
them should be associated with differences in attitude over samples.
Alternatively, attitude toward paying might manifest in exactly the same form if respondents
in different samples perceive similar issues to be at stake where paying for stormwater pollution
abatement interventions are concerned. In other words, the attitude would not be invariant over
different
methodological conditions
so that
changes in these conditions may not solve the presence of protest beliefs.
The process of invariance testing begins with a test of ‘configural invariance’ Steenkamp and
Baumgartner, 1998. This test concerns the extent to which the model takes the same form in each
group i.e. has the same pattern of zero and non-zero factor loadings. If configural invariance
is established, the model’s ‘metric invariance’ can be ascertained by placing equality constraints on
the factor loadings contained in the
L matrix in each group. This step is determined on the basis
of a x
2
difference test between models with and without the equality constraints. If this test is not
significant then it supports the conclusion that the attitude is comparable in each sample. In other
words, the attitude is represented in each group by an equivalent set of indicators associated with
loadings that are not significantly different in either their magnitudes or their variances. Next,
by placing equality constraints on the relation- ships between the exogenous and endogenous
variables in the model contained in the
G and B matrices, conclusions can be drawn about the
invariance of the structural relationships in the presence of methodological variations.
1
4. Method
Two hundred and ten households were selected within an urban watershed located in one of four
Australian state capital cities i.e. Brisbane, Syd- ney, Melbourne, and Perth. All four watersheds
were relatively small : 1500 households and residential. The watersheds were part of a larger
longitudinal stormwater management study, con- ducted by the Australian Research Center for
Water in Society at the Commonwealth Scientific and Industrial Research Organization Nancar-
row et al., 1995, 1998.
1
The process of invariance testing need only concern the matrices of theoretical interest Bollen, 1989, although
configural and metric invariance need to be established before other matrices can be tested for invariance. Moreover, full
invariance i.e. when all elements within a matrix are not significantly different over groups can be relaxed under cer-
tain conditions see Byrne et al., 1989. For example, when a particular matrix is not invariant, researchers instigate modifi-
cations by freeing certain elements across groups in order to ascertain which parameters in the model vary significantly.
Table 1 Differences among the CV surveys
Sample Characteristic
Melbourne Sydney
Perth Brisbane
Trust fund Local government
Payment vehi- Membership fee, andor local
Trust fund drainage levy
cle government levy
Payment Each year
Each year for 4 years Each year Each year for 4
regime years
Sediment removal, litter re- A continuous deflec-
Sediment removal, revegetation, Intervention
Artificial wetland tion system unit
street sweeping, drain education moval, litter baskets, street
sweeping Two local councils, state water
City council Two local councils
Implementing Local council, andor Centennial
institution agency, quasi-government
Park and Moore Park Trust agency
CV interview schedules, response cards, and information
booklets were
developed in
cooperation with state water agencies to depict stormwater pollution abatement interventions
for each watershed. In each watershed, the pro- posed
intervention aimed
to improve
the efficiency of the existing pollution abatement sys-
tem. The interventions relevant to each water-
shed are
summarized below.
Some of
the most salient differences among the four CV sur-
veys are also summarized in Table 1. More detailed
information regarding
the study
methods and materials is given in Nancarrow et al. 1998.
4
.
1
. The Litoria watershed inter6ention in Perth A works program was proposed that would: 1
clean out the existing sediment ponds more fre- quently; 2 plant more reeds and trees around the
sediment ponds; 3 plant 20 trees and shrubs around the main drain leading to the receiving
waters; 4 double the existing frequency of street sweeping; and 5 increase drain eduction from
one to four times a year. Photographs of the existing ponds, street sweeping operation, and
main drain were included in the information booklet. Respondents were told that they would
be required to make contributions to a trust fund each year in order for the works program to
proceed.
4
.
2
. The Ricketts Point watershed inter6ention in Melbourne
The intervention sought to improve the removal of stormwater pollutants such as litter and fine
sediments by installing and maintaining an in-line continuous deflective separation CDS unit in the
main underground drain before it discharged to the receiving waters. The operation and proposed
location of the CDS unit were detailed in the information booklet. For example, respondents
were informed that the CDS unit could remove 100 of the litter and coarse sediment in the
stormwater, as well as most of the existing levels of fine sediment. The money for the intervention
was to be collected through the introduction of a local government drainage levy, to be paid each
year for 4 years by all ratepayers in the watershed.
4
.
3
. The Queens Park watershed inter6ention in Sydney
In the Sydney watershed, three agencies were responsible for stormwater disposal. Stormwater
management within the watershed was the respon- sibility of the Waverley and Randwick councils.
However, management of the stormwater entering the catchment’s sediment pond in Centennial Park
was the responsibility of the Centennial Park and Moore Park Trust. The scenario proposed to
equip an additional ten roadside pits with litter baskets, and to triple the existing frequency of
street sweeping. Within Centennial Park, the in- tervention included an increase in the frequency
of litter collection in the park grounds and from the litter traps in the drain leading to the sediment
pond. The introduction of a pond sediment re- moval strategy was also proposed to take place
every 5 years. Respondents were given the oppor- tunity to make an annual contribution to a local
government levy andor to membership in the Centennial Park and Moore Park Trust’s ‘Friends
of Centennial Park’ Group.
4
.
4
. The Wa6ell Heights watershed inter6ention in Brisbane
The Brisbane intervention proposed an artificial wetland be built in parkland at the bottom of the
watershed. Respondents were told that the wet- land would require an area of 2 ha or 2 of the
watershed. A diagram and photographs were in- cluded in the information booklet to show respon-
dents
how the
wetland achieved
cleaner stormwater, and what it would look like when
completed. Respondents were informed that up to 80 of sediment and 60 of phosphorus could be
removed from the stormwater by the artificial wetland. For the wetland program to proceed,
respondents were told that they would be required to make contributions to a trust fund each year
for 4 years.
4
.
5
. Materials All
necessary information
regarding the
stormwater interventions was included in a book- let that was read aloud to respondents by trained
and experienced interviewers. Full color informa- tion booklets were also provided to respondents
so that they could monitor and clarify informa- tion provided by the interviewers. Each booklet
began with a map identifying the watershed in which the respondent resided. Stormwater was
defined as water that runs off homes, buildings, car parks, roads and building sites. Respondents
were informed about the existing local disposal system with the assistance of photographs show-
ing the local main drain, drainage pits, and receiv- ing waters. Next, the sources of stormwater
pollution and their effects on humans and the receiving waters were explained. In addition, ex-
isting stormwater abatement strategies in the re- spondents’ watersheds were proposed e.g. their
frequency and effectiveness. Finally, the relevant intervention was presented to respondents as a
means of improving the quality of the stormwater emanating from their watersheds. This section of
the booklet showed how the intervention repre- sented an improvement to the existing strategy by
pointing to pollution reductions arising from 1 increases in the frequency of existing services e.g.
street sweeping; 2 increases in the number of existing abatement mechanisms e.g. litter bas-
kets; andor 3 the introduction of more effective pollution abatement technology e.g. artificial
wetland. In addition to the information booklets, respondents were presented with a card summa-
rizing the existing and proposed pollution abate- ment strategies and asked to consider factors such
as current expenses and household income.
The prices offered to equal proportions within the samples were 10, 30, 70, 160, and 350 for
Perth, Melbourne and Sydney. The prices associ- ated with the intervention in Brisbane were 50,
100, 200, 400, and 700. These prices were se- lected on the basis of an earlier large sample study
utilizing
both open-ended
and dichotomous
choice elicitation formats for WTP for stormwater pollution abatement Nancarrow et al., 1995.
Small scale, face-to-face pretests of the interview schedule and materials were also conducted.
Following the WTP elicitation question, re- spondents were asked to respond to a number of
belief statements regarding paying for stormwater pollution abatement Table 2. Notice that protest
2 and 3 in Table 1 differed slightly from the other items with their focus on beliefs about govern-
ment spending. It is plausible that respondents might hold a negative attitude toward paying and
yet feel indifferent or even favorable toward government. Alternatively, people may feel in fa-
vor of paying, but still believe that the govern- ment wastes money. In both cases, attitude
toward government efficiency and attitude toward paying for stormwater pollution abatement may
be independent concepts. Thus, while the variabil- ity in these two items may reflect attitude toward
paying, their error variances may covary due to the
shared influence
of attitude
toward government.
The six belief statements were developed on the basis of previous stormwater management re-
search conducted with participants from the same populations Nancarrow et al., 1995; Jorgensen et
al., 1999 as well as research using samples from other populations Lindsey, 1994. Agreement or
disagreement with each statement was recorded on 5-point Likert scales. Interviewers were in-
structed to vary the order of presentation for each statement, so as to control for response
effects.
Toward the end of the interview, respondents were asked to provide information about their
annual gross household income, age, and level of education. Income was measured with ten cate-
gories that were consistent with those used in the Australian census. These categories ranged from
‘ B 5000’ to ‘ \ 80 001’. Missing values on the income question amounted to 19 respondents in
Perth, 59 in Melbourne, 28 in Sydney, and 31 in Brisbane. Missing data imputation was under-
taken in Prelis 2 Joreskog and Sorbom, 1996a using responses to the age and education ques-
tions as variables with matching response pat- terns. Imputation substitutes real values for
missing values on the basis of cases that have matching ages and education levels. In
order to enhance precision in the estimation pro- cedure, only values predicted with a variance ratio
of B 0.5 were imputed. The variance ratio is calculated
by dividing
the variance
of the
income values of the matching cases, by the total variance of the complete data on income.
Following this procedure, 9, 30, 8, and 14 missing values on income were imputed in the Perth,
Melbourne, Sydney, and Brisbane samples, re- spectively.
The total samples sizes in each group were 177 Perth, 171 Melbourne, 164 Sydney,
and 174 Brisbane after accounting for ‘don’t know’ responses on the WTP question and
missing values.
Twenty-three respondents
in Perth, 7 in Melbourne, 13 in Sydney, and 22 in
Brisbane did not know whether they would be WTP for additional stormwater pollution abate-
ment.
Table 2 Description of attitude toward paying items
Item label Item description
Protest 1 It is unfair to ask me to pay more money
for stormwater pollution controls Protest 2
The government should use existing rev- enue to pay for stormwater pollution con-
trols Protest 3
We would be able to afford better protec- tion of receiving waters already if the
government did not waste so much money It is my right to have cleaner stormwater
Protest 4 and not something I should have to pay
extra for Protest 5
If the money was collected, I don’t really believe that it would be spent on making
the stormwater cleaner Protest 6
I pay enough already in government and council charges for cleaner stormwater
Table 3 Descriptive statistics of variables in the model
a
Variable Sample
Perth Sydney
Brisbane Melbourne
Price 2.89
1.24 1.22
1.17 2.36
1.21 1.23
1.22 6.76
6.35 4.66
4.66 Income
2.61 2.91
2.25 2.11
3.40 2.73
Protest 1 2.94
3.43 1.39
1.34 1.39
1.27 3.90
3.91 4.08
4.06 Protest 2
0.97 1.08
1.13 1.04
4.44 Protest 3
4.60 3.73
4.03 0.87
1.28 1.23
1.03 Protest 4
3.47 2.97
3.07 3.59
1.20 1.35
1.35 1.36
3.38 3.57
Protest 5 3.48
4.06 1.04
1.17 1.12
1.25 3.98
Protest 6 3.57
3.48 4.06
1.04 1.17
1.25 1.12
1.55 1.75
1.65 WTP
b
1.50 0.50
0.43 0.48
0.50
a
S.D. in parentheses.
b
Refusals to pay the stated price were coded ‘1’ while willingness to pay the price given in the survey was coded ‘2’.
5. Results
