4.2.1 Sample Size
Sample size can be crucial in determining the accuracy of the CVM and TCM
estimation. Larger sample sizes imply larger costs, but at the same time the larger the
correctly-selected sample, the greater the accuracy of estimation would be. However, to
the author’s knowledge, no specific study has been carried out specifically to address
the ideal sample size for dichotomous choice contingent valuation studies and/or travel
cost method.
In general, Roscoe in Sekaran (1992) proposes rules of thumb for determining sample
samples that are broken into sub-samples, a minimum sample size of 30 for each
category is necessary”. As a further guideline, Calia and Strazzera (1998) in their study
on bias and efficiency of single vs. double bound CVM model, define “small size
sample” as sample of 100 or less; categorize sample size of 250 – 400 as “medium size
sample”; and more than 1000 as “large sample size”. They conclude that even for a
medium sample size, both single and double bound CVM perform well in giving point
estimates for the parameters and of the mean WTP.
According to Ward and Beal (2000), many investigators conducting small to medium-
scale (that is, not a national survey) Travel Cost studies like to have 300 – 500 usable
records. So, if the response rate were expected to be about 20 per cent, the selected
sample to gain 500 records would have to be 2,500. If, on the other hand, the response
rate were expected to be about 50 per cent, the selected sample would only have to be
1,000.
In conclusion, given the limited time and budget constraints, we targeted to obtain at
least 600 responses for both the TCM and CVM analysis.
4.2.2 Survey Design and Data Collection
The questionnaire was constructed to be as easily comprehensible as possible for the
respondents due to past experience on the part of the researcher. Respondents would
usually be busy in the water that the time available for them to allocate for answering
that the respondents were guided (answers are given in terms of options and they just
have to tick boxes). From the pilot study done, respondents take, at most, 15 minutes to
complete the questionnaire.
An in-person interview was conducted as we feel that it is very important for the
respondents to fully understand the issues in the questionnaire. For this study, there are
two issues raised. The issues are set separately in two sets of questionnaires. The issues
that the researcher raised are about the effect of too many tourists on the parks; and the
effect of inland development on the corals. Both sets of questionnaire have the same
questions on section one and two but only the third section has some differences on the
issues (Sample of the questionnaires is in Appendix 3).
In both cases, the first section aims to capture the background information on
respondents. Questions 1 to 6 are on the country of origin; sex; age; highest education
level attained; annual household income; and occupation. Questions 7 to 10(d) concern
the respondent’s visits to the marine park. How many times have they visited the park is
asked in question 7 and 8 and activities that interest the respondent most is the subject
of question 9. Questions 10 a to 10 d are on the opinion of the respondents on attributes
of the park such as the water visibility; fish species; corals variety and development
around the marine park that the respondents visited. This section also gathers
information on whether respondents are members of any environmental group and the
name of the group, and also whether they have visited other marine parks other than this
Section 2 concerns journey information. Questions included are the point where the
respondents started their journey, time of the journey and the number of persons they
travel with. Respondents’ are also asked about their spending to come to this marine
park on petrol (if travel is by car); bus fare or flight fare; boat; accommodation; and
others; or if they come with a tour package, the price of their package.
The third section as mentioned above is different between the two sets of questionnaire.
This section tries to elicit the willingness-to-pay of the respondents to this marine park.
The first thing done in this section is the set-up of the hypothetical market for the
marine parks. The hypothetical market is crucial since marine parks do not have a well-
defined market and it is important for the respondents to understand the issues in the
hypothetical market so that they know what they are paying for. The hypothetical
market was set up to explain the issue of damage to corals done by human beings. The
issue of the effect of inland development on corals is stated in the questionnaire as
below:
Coral reefs are not only beautiful but also important for many reasons. Most importantly, they provide protection and shelter for many different species of fish. They also control how much carbon dioxide is in the ocean water; protect coasts from strong currents and waves by slowing down the water before it gets to the shore; and hold promise for scientists seeking new drugs to combat disease such as cancer. Furthermore, they also generate income to one’s country from tourism industry; second largest to Malaysia.
Nearly 80% of the reefs of Southeast Asia, the most species-rich on earth, are at risk, and more than half at high risk. Soil erosion, from deforestation or cultivation on steep slopes, when transported by rivers into coastal waters can smothers corals, preventing oxygen and nutrients from reaching coral polyps and preventing coral larvae from settling and forming new colonies. Sewage discharge from coastal communities promotes growth of algae that blocks sunlight, which corals need to survive.
One way to protect corals from these kinds of damage is by establishing marine parks, to protect and conserve the marine eco-system, especially coral reefs. Right now, the authority is charging RM5.00 (equal to USD 1.30 or less than GBP 1.00) to every visitor to this marine park, but they only take care of the water areas, NOT the inland activity.
The statement is followed by questions as below:
If the authority wanted to combat threat to corals in this park from inland activity
by 1) treating sewage before it reaches reefs (which benefits human health too); 2)
promoting economic activities that are good for both reefs and people; 3) implementing
coastal zone management and planning; 4) and hiring more people to monitor and
enforce rules and regulations, AND increase the charge to RMXX would you be
willing to pay to visit this park?
Yes No
The above questions are to give current scenarios and the hypothetical situations to the
respondents. So, if they said “yes”, they know what they are paying for; that is paying
to reduce the damage to coral reefs. Since the researcher choose to use a referendum
format question, pre-chosen amounts of willingness-to-pay are set. The discrete choice
nature of the question provides respondents with a straightforward option of “yes” or
“no”. Less burden is placed on respondents because they are not required to determine
their exact maximum willingness to pay, rather only whether they are willing to pay at
least the amount asked.
There are 6 different bids given to different respondents randomly. Each respondent
RM10.00, RM15.00, RM20.00, RM25.00, RM35.00, and RM65.00. The same bids are
used in both issues. The charges are chosen based on the previous study done on Payar
Marine Park (Ayob et al., 2002) and a pilot study done by this researcher. In a pilot
study on 50 respondents, researcher listed possible payment that respondents might be
willing to pay above the current fee (RM5.00). The lists are as below and the
respondents needed only to circle the highest payment they agreed to pay:
8 10 15 18 20 23 25 28 30 32 35 38 40 42 45 48 50 53 55 60
63 65 68 70 72 75 78 80 83 85 90 100
In the pilot study, the lowest WTP circled was RM8 and the highest WTP circled was
RM80. However, only two respondents circled RM80. Therefore, RM10 and RM65
were chosen as the lowest and highest WTP respectively. Same method is used by Hall
et al. (2002) to determine bid values; based upon results from pre-testing or pilot test.
They used open-ended questions which give them values from USD0 to USD260. They
choose to place a bid from USD2 up to USD100.
Since the researcher also chooses the double-bounded discrete-choice elicitation method
(Hannemann et al., 1991) besides the single-bounded dichotomous choice valuation, the
next question is to increase the WTP by RM5.00 if the respondent said YES to the
above question and the next question is decreased the WTP by RM5.00 if the
respondent said NO to the above question. The RM5.00 increase and decrease is chosen
because of the payment that respondents choose in the pilot test. RM5.00 is considered
a minimum increase/decrease that they feel is reasonable. For example if the first
If YES, would you be willing to pay RM25.00? Yes
No
If NO, would you be willing to pay RM15.00?
Yes No
The second issue was raised by putting a statement in the questionnaire as below:
Coral reefs are not only beautiful but also important for many reasons. Most importantly, they provide protection and shelter for many different species of fish. They also control how much carbon dioxide is in the ocean water; protect coasts from strong currents and waves by slowing down the water before it gets to the shore; and hold promise for scientists seeking new drugs to combat disease such as cancer. Furthermore, they also generate income to one’s country from tourism industry; second largest to Malaysia.
But tourism, when unregulated, can pose problems. Tourists are capable of loving a reef to death. Snorkellers can be a threat to the corals by accidentally kicking up sediment that can suffocate the corals. Snorkellers can also stand on the corals. This seems to be the case in Payar, where corals within 1 km from the shore are all dead. Divers also can damage corals by accidentally bumping into reefs because the water they are in is too shallow, or by scraping corals with diving equipment.
The next questions (question 21 and 22) are posed as below:
21. In 2000, the number if visitor to Payar was 106,780; Redang 52,674 and Tioman
48,942. In your opinion, do you think there are too many people in the park today?
Yes No
22. Suppose the authority wants to limit numbers of visitors to half the number who
RMXX (currently RM5.00 or equal to USD 1.30 or less than GBP1.00) and you
were entitled to visit this marine park, would you still have visited today?
Yes No
This set of questionnaire also uses the double-bounded discrete-choice elicitation
method as in the inland development issue. The follow-up questions are done the same
way as the inland development issue explained earlier.
The second thing to decide in constructing the questionnaire is to decide on the vehicle
payment. There are many different possible bid vehicles namely income tax, value
added or sales tax, trust fund payments, property taxes, changes in utility bills and entry
charges. Certain bid vehicles are only suitable and viable in a certain given situation.
According to Garrod and Willis (1999) the chosen bid vehicle should have a plausible
connection with the amenity it is being used to value, and also be perceived to be ‘fair’
and ‘equitable’ in its incidence and in relation to those deriving benefits for the
proposed good. In this study, the vehicle payment used is the entry fee to the marine
park. This vehicle is used because the park has charged RM5.00 per adult since early
2002. Furthermore, since the survey is done on the site, there will be no free raider issue
here. So, this study attempts to obtain the consumer surplus2. A study by Mathieu,
Langford and Kenyon (2000) also used an entrance fee as payment vehicle to elicit
consumer surplus while Leon (1996) choose a contribution to a fund to “introduce some
neutrality by comparison with other payment vehicle…”
2 Consumer surplus is defined as the difference between what people would be willing to pay for a good or a service and what they actually pay (Pearce and Turner, 1990).
This section also tried to capture the reasons the respondent were willing to pay the bid
posed to them if they say YES to either first bid or second bid and the reasons they do
not want to pay if they say NO to both bids. Reasons for not willing to pay at all are as
below:
1. I feel the visitors to this marine park do not harm corals
2. I do not believe increasing the fee would solve the problem
3. I do not agree that visitor numbers should be limited
4. I fail to understand the question
5. Other (please specify)
The last reason (other) will also capture protest bids. The respondent can choose more
than one answer.
The reason for respondent’s willingness-to-pay is as below:
1. For my own benefit
2. For society as a whole
3. For the next generation
4. Others (specify)
Reasons above can be categorised as use-value, option value and bequest value. This
will capture the use and non-use value of the respondent’s WTP. The respondents can
Before the main survey was conducted, a pilot study was performed. The pilot study
was undertaken in Payar due to its location near to the researcher’s home and also
because of the season. The pilot test was conducted in December 2002. At this time,
Malaysia was under the monsoon season where the east coast of Malaysia had strong
winds and rough sea. Due to this, the pilot test was conducted only in Payar because
Payar is the only Marine Park on the west coast. The pilot test was used to test whether
respondents can understand the questions posed in the questionnaire and also to capture
the range of WTP of the visitors. The researcher went to Payar twice for the pilot test in
the second and third week of December 2002. 20 questionnaires were collected.
Researcher did the survey on her own to get detailed comments on the questionnaire
and luckily the visitors were very cooperative.
After the pilot test, minor corrections were made and sets of WTP bids were chosen. A
major correction was on the description of the issues; it was shortened due to the
respondent’s complaint for having to read long passages. Therefore the researcher
decided to make it as short as possible.
In-person interviews of foreign and local tourists were carried out in three of the main
marine parks in Peninsular Malaysia. The three marine parks chosen for this study are
Payar, Redang and Tioman. They are chosen for the following reasons:
1. Locations – Payar is located in the west coast of West Malaysia while Redang
and Tioman are in the east coast of Peninsular Malaysia.
2. Attractions – the three marine parks have some degree of differences and
3. Fees – all three parks charge their visitors some conservation fees in the form of
an entrance fee.
The first survey was done in Payar within 2 months starting from 2nd January 2003. The
researcher went 7 times to Payar and managed to get 206 questionnaires filled. Only
205 are used since one of the questionnaires are not fully filled. It is pretty hard for the
researcher to approach the visitors due to the situation in Payar where visitors normally
have only 4 to 5 hours only on the beach. Payar, being a very small island without fresh
water facilities, has only day trip visitors. The visitors normally arrived in Payar
between 10 and 11 in the morning and left at 3 or 4 in the afternoon. At all times,
visitors are busy in the water or on the beach for lunch. The researcher will have to wait
for the visitors who relax on the beach to be interviewed. Therefore, the researcher and
the two enumerators approached those who appear convenient to be interviewed with no
particular specification chosen for sampling.
For Tioman, the number of days on which the survey was undertaken was longer
because the researcher had the help of an officer of the Fisheries Department, Malaysia
to distribute the questionnaires through students undertaking practical study in Tioman.
The time range for survey in Tioman took two months between early May until the end
of June. The researcher gave briefings to those students about the questionnaire and
how to approach the visitors and what to answer if being asked by the visitors. But from
the researcher’s experience in Payar, the questionnaire can be self-administered and the
visitors normally do not ask any questions. Tioman is quite a big island with five jetties
Genting. The questionnaire was distributed at all these five places. The researcher went
to Tioman for a week in the first week of May to monitor the survey and collected the
filled questionnaires in from the Fisheries Officer at end of June. A total of 245
questionnaires were collected but only 233 are used since the 12 are not fully
completed.
The researcher went to Redang on the 21 May 2002 with two enumerators. The
enumerators were university students doing their masters degree in economics and were
briefed by the researcher. The researcher and the enumerators stayed in quarters for
staff of Fisheries Department in Pinang Island until 28 May 2002. The questionnaires
were mostly distributed in front of the Marine Park Office in Pinang Island because
most visitors are brought there by the tour operator since this location is rich in corals
and fishes. That is also a place where the RM5.00 environmental charge is currently
collected. Besides that, the staffs of the Fisheries Department were kind enough to bring
the researcher and the enumerators to Perhentian Island and Redang Island for the
survey to be done. A total of 217 questionnaires managed to be collected with useable
questionnaires of 212.
To survey at least 600 respondents with a very limited budget is not an easy task. We
managed to obtain the assistance of two masters students that were studying for their
Masters in Economics in Universiti Utara Malaysia. We offered them explanation and
instruction of the questionnaire and brought them to the marine parks to do the
interview, along with the principle investigator. All together, we manage to collect 650