Sustainability Science
https://doi.org/10.1007/s11625-023-01296-2

TECHNICAL REPORT

Valuation of student‑led agricultural activities at university:
comparison of willingness to pay with inferred values
Ryo Sakurai1· Takuro Uehara1

Received: 4 October 2022 / Accepted: 17 January 2023
© The Author(s) 2023

Abstract
Agricultural fields in university campuses can improve urban nutrition security, increase greenery, and provide opportunities for students to grow crops and enhance self-management skills. We conducted student surveys among freshmen in two
different years (2016 and 2020) to understand their willingness to pay (WTP) for donations toward student-led agriculturalactivities. In order to mitigate the social desirability bias, we also asked students’ inferred WTP and compared that withconventional WTP. We found that inferred values could determine more conservative and realistic estimations of students’
donations than conventional WTP. Full model regression analysis using logit model estimation showed that students’ interest
and engagement in pro-environmental behaviors increased WTP for student-led agricultural activities. In conclusion, suchprojects are economically feasible through student donations.
Keywords Willingness to pay · Inferred value · Student survey · Pro-environmental behaviors · Agriculture

Introduction
Creating community gardens and agricultural fields in urban
areas can improve urban food and nutrition security, increase
greenery in residential areas, and facilitate participatorycommunity building to revitalize neighborhoods (Silva andRamirez 2018; Russ and Gaus 2021). Urban agriculture canbe defined as a form of farming or gardening implemented incities, and includes community gardens, school gardens, andurban organic farms (Russ and Gaus 2021). Easy access togreenery and/or agricultural fields enhances the well-being
and quality of life for urban residents (Tan et al. 2017), andprovides environmental education opportunities, especially
if such fields are created in the campuses of educational
institutes (Pevec et al. 2017). Having greenery on campus
enables students to experience nature and grow plants andcrops. By independently managing such gardens and fields,
they can also develop self-management and teamwork skills(Russ and Gaus 2021). Globally, having community gardens/
Handled by Faik Bilgili, Erciyes University, Turkey.

agricultural fields on campus helps students gain knowledge
about growing foods, understand food security, and obtaininsights into managing and creating their own nourishment(Pevec et al. 2017; Silva and Ramirez 2018). In addition, by
utilizing the recently developed concept of regenerative agriculture which aims for lower or net positive environmental
and/or social impacts in terms of processes (e.g., integrationof livestock) and outcomes (e.g., to increase biodiversity)(Newton et al. 2020), urban agriculture could contribute tocreation of a sustainable society. However, limited researchhas been conducted to understand students’ perceptions
about—and economic valuations of—creating agricultural
fields on campus, and their willingness to get involved insuch food production activities (Russ and Gaus 2021).
To respond to this gap, we conducted a survey to understand how students value efforts to create agricultural fields
on campus by enquiring about their willingness to pay(WTP). We assumed that merely asking students their WTP
through stated preference methods would generate biases,
primarily social desirability bias, so we also asked theirinferred value (i.e., how much they thought their friends
would pay).

* Ryo Sakurai
ryo223sak@gmail.com
1

College of Policy Science, Ritsumeikan University, 2‑150,
Iwakuracho, Ibaraki, Osaka 567‑8570, Japan

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Sustainability Science

Previous studies and theoretical backgroundThe stated preference method continues to be one of the
only valuation methods to understand the value of a service that does not necessarily have market value (e.g.,
starting student-led agricultural activities on campus)(Freeman III 2003; Entem et al. 2022). The most commonly used preference approach is the contingent valuation method, where individuals are asked about the levelof their WTP for a certain service. Studies on valuationof ecosystem services include analysis of local residents’
WTP for river restoration (Bliem and Getzner 2012) andtourists’ WTP for environmental protection and eco-tourism (Take and Iida 2016). While the validity of contingent
valuation methods is widely accepted in academia (Boyle
2003: 114), they have certain limitations. For example,
these methods cannot eliminate the potential gap between
hypothetical and real cash transactions. Strategies toeliminate such biases have been developed (e.g., cheap
talk [making sure that respondents answer under realistic
conditions] and identification of respondents’ confidence
level in their answers) (Freeman III et al. 2014: 401–402).
One of the most well-known limitations of general social
surveys is the social desirability bias, in which respondents
provide socially desirable—rather than honest—answers(e.g., overstating their contributions to charitable organizations or for protecting certain natural environments)(Champ 2003: 70; Lopez-Becerra and Alcon 2021). To
mitigate such errors, the inferred valuation method was
proposed (Lusk and Norwood 2009).
In inferred valuation, respondents are asked to estimate
how much another person would be willing to pay in ahypothetical situation. Theoretically, it overcomes thesocial desirability bias, as respondents are assumed togain little or no pleasure or satisfaction by increasing others’ social desirability (Lusk and Norwood 2009). Inferred
valuation was proposed on the basis of studies that showed
how people could more accurately predict their future
behavior by considering other people’s behavior (rather
than their own behavior) (e.g., Epley and Dunning 2000).
Building on previous studies, Lusk and Norwood (2009)
conducted a series of experiments and verified a significant difference between people’s predictions of their own
behavior and their actual behavior. Their own behaviors
were more similar to their inferred values, thus indicating that this measure provides more accurate and realistic
estimates.
Research has supported inferred valuation’s ability toprovide more realistic and conservative estimates thanconventional WTP approaches. For example, a study in
Ireland revealed that stated valuations obtained by the conventional approach were more than three times higher than13

inferred values; thus, it concluded that inferred valuation
is promising for producing conservative estimates (Yadav
et al. 2013). An investigation in Japan demonstrated thatinferred valuations of the economic value of forest ecosystem services were more appropriate as they mitigatedsubjective valuation biases (Tanaka and Nagahiro 2019).
Yet another study in Spain revealed that people stated a
2.8-fold higher WTP for protection of a coastal area thantheir inferred value, thereby implying significant social
desirability bias (Lopez-Becerra and Alcon 2021). In Canada, people’s stated WTP for protecting at-risk species
was more than two times higher than their inferred value(Entem et al. 2022).
However, while research on inferred valuation isincreasing, very few studies have investigated students’
inferred values for creating sustainable campuses throughparticipatory agricultural activities. Understanding theactual cost and how to budget for the creation of facilities
such as agricultural fields enables decision-makers to evaluate the feasibility of such projects. Previous studies haveshown that students were willing to donate to improvetheir campus environment; the estimated sum of their
WTP exceeded the actual cost necessary for implementation of the project (Sakurai and Uehara 2017). If the costof creating agricultural fields on campus, including initialand running costs, could be covered by student donations,such projects would be sustainably implemented without
requiring the financial support of the university or otherentities. However, supporting the creation of agricultural
fields could be considered a morally and socially desirable
attitude (Epley and Dunning 2000); thus, the social desirability bias means that merely asking students their WTP
for such activities could produce value overestimations.
Therefore, inferred valuation is necessary to explore thetrue value of students’ WTP in this regard.
Most, if not all, previous studies on inferred valuation
implemented a one-time measurement of certain welfare.
However, people’s valuation of a certain service couldchange depending on aspects of the context that are specific to the time when the survey was conducted. To test
the validity and reliability of inferred valuation methods,
we conducted studies in different years (i.e., freshmen
students in 2016 and 2020) to identify inconsistencies instudent valuations.
Therefore, building on previous studies that showed
how inferred valuation could provide conservative andrealistic estimation (e.g., Lusk and Norwood 2009; Tanaka
and Nagahiro 2019; Entem et al. 2022), our first hypothesis
was that students’ inferred values for donations toward
student-led agricultural activities would be significantly
smaller than their own subjective valuations. The second
hypothesis was that inferred and subjective valuations forSustainability Science

the same service by students in different years would bealmost identical (i.e., not significantly different).

Calculation
The theoretical background of inferred value calculation canbe shown following the equation for utility [U] (Lusk andNorwood 2009; Tanaka and Nagahiro 2019):
(
) (
) (
)
U = wNH M A = WTPNH , H + 1 − wNH V I − WTPNH , E .
(1)
M is utility obtained by conducting socially desired
behavior, and A indicates the actual behavior displayed. In
this study, donating to student-led agricultural activities is
the socially desired behavior. H represents the individual’s
honesty level; H decreases as the gap between WTP andactual amount paid increases. While V(・) is the general utility, I represents income and E represents sustainable environmental quality for the campus in this study. If one donates,
their income declines (I − ­W TPNH) while environmental
quality increases (E → E′). wNH is the weighted score thatshows the relative importance of M(・) and V(・) (0 ≤ wNH ≤ 1).
The more the donation towards student-led agriculturalactivities is recognized as socially desired behavior, the bigger the value of wNH affecting M(・). As starting student-led
activities and making donations is hypothetical, NH (nonhypothetical) in the equation is actually H (hypothetical).
Our analysis is based on the theoretical assumption that, as
expressing willingness to donate and showing honesty bothincrease utility (MA > 0, MH > 0), hypothetical WTP will bebigger than actual WTP ­(WTPH > ­WTPNH).

Methods
This study was conducted among students at the College of
Policy Science at Ritsumeikan University, one of the biggest
private universities in Japan, with nearly 30,000 undergraduate students. Approximately 1,600 undergraduate students
belong to this college, and they learn a variety of policyscience-related subjects and disciplines. Therefore, students
were not necessarily studying environmental issues but hadvarying interests across multiple areas. The first survey
was conducted on 12 April 2016 among college freshmen(n = 375); it was distributed in a course named “Introduction to Social Research Methods,” a mandatory course for
all freshmen. Similarly, the second survey was conducted
in 2020 among freshmen (n = 356) in the same course. We
chose four years as the gap to test validity of inferred value
in this study. This is because in four years, all if not most of
students graduate from university; most of the students who
answered the survey in 2016 as freshman were expected tograduate university by the end of 2019, and therefore, we
can assume that those who answered the survey in 2020
are totally new and different groups of students. While students answered the 2016 survey in classrooms, the 2020
survey was web-based (from 31 July to 7 August 2020) as
the course had shifted online because of the COVID-19
pandemic.
For both surveys, the cover letter of the questionnaire
explained the contents and objectives of the research andstated that students’ participation was voluntary. Students
proceeded to answer questions once they provided informed
consent. The questionnaire comprised items regarding attributes (three items), interests in pro-environmental behaviors
and growing organic vegetables (seven items), and actual

Table 1  Question items and response scale
Variable name

Description

Interests in pro-environmental
behaviors and growing organic
vegetables

I am interested in recycling
1. Disagree, 2. Slightly disagree, 3. Neither
agree nor disagree, 4. Slightly agree, 5.
I am interested in nature conservation on campus
Agree
I am interested in utilizing renewable energy
I am interested in using environmentally friendly goods
I am interested in growing my own vegetables
I am interested in eating vegetables I have grown
I am interested in eating organic vegetables
I turn off lights as much as possible in my house
I bring my own bag when I go shopping
I set low temperatures on heatersAge
1. 18, 2. 19, 3. 20, 4. 21, 5. 22 or Older
I have a part-time job
1. No, 2. Yes
I receive an allowance or financial support from my parents

Pro-environmental behaviors

Attributes

Response scale13

Sustainability Scienceengagement in pro-environmental behaviors (three items)(Table 1).
To determine an individual’s WTP, we used dichotomous-choice questions, which required participants toanswer whether they would agree or decline to donate different amounts. Double-bound questions were used, in which
participants who agreed to pay the first bid were presented
with a higher bid (double the initial amount) in the following
round; those who declined to pay the initial bid were showna lower bid (half the initial amount) in the succeeding round.
We distributed five versions of the survey with different bid
amounts (Survey A: 500 yen [approximately $5]; Survey
B: 1,000 yen [approximately $10]; Survey C: 2,000 yen[approximately $20]; Survey D: 4,000 yen [approximately$40]; Survey E: 8,000 yen [approximately $80]). The different bid amounts were created based on a previous study
that investigated university students’ WTP for environmental
improvements around their campus in Japan, which revealed
that students’ mean and median WTP values were 2,000 and
4,699 yen (Konakayama and Sato 2004). In the survey, we
first explained the hypothetical scenario (creating a studentled agricultural association) as well as actual activities that
could be implemented; they were also told they could eat
crops grown at the Reserve Space (Table 2). We then asked
the respondents their WTP (whether they would donate thesuggested amount) for being able to participate in the student-led agricultural activity. Additionally, we asked them
about their inferred WTP through the question: “Would yourfriends and acquaintances on campus also donate?”.

Analysis
We compared significant differences between the twogroups (students in 2016 and 2020) in terms of their
attributes and cognitive factors by conducting chi-square
and independent t-tests. We then analyzed students’ WTP
and inferred values for student-led agricultural activities
for the samples from 2016 and 2020 based on the simple
logit model using bid as an independent variable. The logit
model assumes that the difference in utility is calculated

as follows: [constant (utility change created by an environmental change) + coefficient * In (bid) + error]. In addition, the rate of agreement is expressed as [1/(1 + exp(− ΔV)] whereas ΔV is a fixed sum of error deduced fromthe difference in utility. The log-likelihood function isexpressed as:

lnL =

N
∑
(
)
(
)
yy
yn
{di ln𝜋yy T, T U + di ln𝜋yn T, T U
i=1

(
)
(
)
ny
+ di ln𝜋ny T, T L + dinn ln𝜋nn T, T L }.

(2)

In this case, dyy is a dummy variable, where 1 denotes
respondents agreeing to donate the second bid and 0 represents all other responses. T is the first bid, T U is thesecond bid when the first bid is agreed on, and TL is thesecond bid when the first bid is declined (a lower amount).
Furthermore, N is an observable variable. Lower and upperbounds of 95% confidence intervals were examined to
identify any significant difference between these values.
Additionally, we conducted a full model regression
analysis using logit model estimation to see what factors
affect WTP and inferred values. Samples from 2016 and2020 were pooled in the full model regression analysis,
where all items (specifically the three attribute factors,
seven factors related to interest in pro-environmental
behaviors, three factors on actual engagement in proenvironmental behaviors, and years [2016 or 2020]) wereused as independent variables. The functional form forthe indirect utility [Vij] of an individual i for alternative jis specified in this study as:

Vij =B0 + B1 AG + B2 PJ + B3 FS + B4 IR + B5 IC + B6 IR+ B7 IG + B8 TL + B9 BB + B10 LT + B11 IV + B12 IEV+ B13 IEOV + B14 YE + B15 log(Bid) + e(3)

Whereas B0 is the intercept, B1 is the coefficient for age(AG), B2 and B3 are the coefficients for part time job (PJ)
and financial support from parents (FS). B4, B5, B6, and B7
are the coefficients for interested in recycling (IR), nature

Table 2  The scenario presented in the survey (different bid amounts are demonstrated for each survey [Survey A: 500 yen; Survey B: 1,000 yen;
Survey C: 2,000 yen; Survey D: 4,000 yen; Survey E: 8,000 yen])
There is an open area called the “Reserve Space” in the southern part of the campus. We have been considering converting part of theReserve Space into agricultural fields where students could grow vegetables for their own consumption (this is a hypothetical scenario;
it is not necessarily being considered by the university). A newly created student-led agricultural association will grow crops, whilestudents who are interested in growing crops could participate in this activity. Additionally, students who belong to the campus could eat
crops grown at the Reserve Space
In order to create agricultural fields (10 m * 30 m), soils, nutrition, and seeds need to be prepared. Initially, running costs for student-led
agricultural activities (fees for cultivating agricultural fields and growing crops) will be paid by students who support the implementation of this initiative. However, if sufficient donations are not obtained and the student-led agricultural association is not established, theReserve Space will continue to be an open groundIf you were asked to donate XXX yen (as a one-time payment for the entire study period), would you do so? However, keep in mind that if
you were to donate the requested amount, you would naturally have less money to spend on other products or services

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Sustainability Science
Table 3  Students who were doing part-time jobs and receiving financial support from their parents
Frequency (%)
2016 (n = 364)

Chi-square score

p value

29.282< 0.01

1.330

0.249

2020 (n = 336)

Part-time job
Yes 271 (74.5)
303 (90.2)
No 93 (25.5)
33 (9.8)
Financial support from parents
Yes 163 (44.9)
166 (49.3)
No 200 (55.1)
171 (50.7)

conservation on campus (IC), utilizing renewable energy(IR), and using environmentally friendly goods (IG). B 8,
B 9, and B 10 are the coefficients for turning lights off asmuch as possible (TL), bringing my own bag (BB), andsetting low temperatures on heaters (LT). B 11, B 12, andB13 are the coefficients for interested in growing my own
vegetables (IV), eating vegetables I have grown (IEV), andeating organic vegetables (IEOV). B14 is the coefficient foryear (YE), B15 is the coefficient for log(Bid), and e stands
for the error.
SPSS (IBM) was used for descriptive analysis and chisquare and t tests. R was used to calculate WTP and inferredvalues and to conduct the full model regression analysis. p
values of 0.10 were set as the significance threshold.

Table 4  Students’ interestsand engagements in proenvironmental behaviors

Results
A majority of students in 2016 and nearly half of the students in 2020 were 18 years old; in both years, more than
90% of students were either 18 or 19 (Appendix 1). Whilea majority of students had part-time jobs in 2016, almost
all had part-time jobs in 2020 (Table 3); chi-square tests
revealed this difference was significant (p < 0.01). The percentage of students who received financial support fromtheir parents was approximately 50% in both 2016 and 2020.
Students generally agreed that they were interested inengaging in pro-environmental behaviors, but those in 2020
showed significantly higher interests (p < 0.01) in recycling, conservation of campus, utilizing renewable energy,
and using environmentally friendly goods (Table 4). As
for behaviors, students in 2020 were more likely to answer
positively to the factors “bring my own bag” and “set low
temperatures on heaters” (p < 0.01). Meanwhile, students in2016 were more likely to be interested in growing their own
vegetables than those in 2020 (p < 0.05).
After excluding protest responses (e.g., those who disagreed to donations as a measure), we calculated students’
WTP for donating to student-led agricultural activities. For
students in 2016, the mean WTP (truncated at the maximumbid) was 1613.6 yen (approximately $16) with a median ofMean Standard t scoredeviation
Interests
Interested in recycling
Interested in nature conservation on campusInterested in utilizing renewable energy
Interested in using environmentally friendly goods
Interested in growing my own vegetables
Interested in eating vegetables I have grown
Interested in eating organic vegetables
Behaviors
Turn off lights as much as possible
Bring my own bag
Set low temperatures on heaters

2020 (n = 336) 3.96
2016 (n = 365) 3.34
2020 (n = 335) 3.53
2016 (n = 365) 3.25
2020 (n = 336) 3.91
2016 (n = 365) 3.60
2020 (n = 336) 4.02
2016 (n = 365) 3.50
2020 (n = 336) 2.75
2016 (n = 363) 2.97
2020 (n = 337) 2.99
2016 (n = 364) 3.09
2020 (n = 335) 3.23
2016 (n = 364) 3.31

0.94
1.03
1.12
1.08
0.95
1.05
0.90
1.07
1.30
1.28
1.37
1.28
1.29
1.27

2020 (n = 335) 4.02
2016 (n = 364) 3.93
2020 (n = 337) 3.98
2016 (n = 365) 2.77
2020 (n = 337) 3.52
2016 (n = 365) 3.26

1.14
1.20
1.29
1.48
1.27
1.33

p value

8.439< 0.013.400< 0.01

4.109< 0.016.909< 0.01− 2.253 0.03
− 0.934 0.35
− 0.829 0.41

1.076

0.28

11.616< 0.01

2.722< 0.0113

Sustainability Science

1101.3 yen (approximately $11; n = 111). Mean inferred
WTP (truncated at the maximum bid) was 1056.6 yen(approximately $10) with a median of 742.4 yen (approximately $7; n = 58). In both years, WTP was more than 200
yen higher than inferred values for both means and medians. However, these differences were not statistically significant, as confidence intervals of WTP and inferred values
overlapped.
As for 2020, the mean WTP (truncated at the maximumbid) was 2376.8 yen (approximately $23) with a median of1408.8 yen (approximately $14; n = 107). Inferred WTP(truncated at the maximum bid) was 1814.5 yen (approximately $18) with a median of 1150.6 yen (approximately$11; n = 66). As the confidence intervals for both the means
and medians overlapped, there was no significant difference
between WTP and inferred values for the year 2020 (Fig. 1).
The results of the full model regression analysis (n = 216)
revealed that seven independent variables significantly
affected students’ WTP (Table 5). Respondents who wereinterested in using renewable energy (B = 0.579, p < 0.01),
growing their own vegetables (B = 0.422, p < 0.05), nature
conservation on campus (B = 0.347, p < 0.05), brought theirown bags (B = 0.211, p < 0.1), and turned lights off as muchas possible (B = 0.050, p < 0.05) offered higher WTP values.
On the other hand, respondents who set low temperatures onheaters offered lower WTP values (B = − 0.203, p < 0.1). In
addition, independent variable of log (Bid) had significant
negative influence on WTP (B = − 2.021, p < 0.01) which isunderstandable as respondents’ income decreases by paying
higher bids which in turn decreases their utility. The mean
Fig. 1  Students’ mean andmedian WTP and inferredvalues for student-led agricultural activities (CI = 95%
confidence interval with lower
and upper bound; n = 111 for
WTP and n = 58 for inferred
WTP in 2016; n = 107 for WTP
and n = 66 for inferred WTP in
2020)

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WTP (truncated at the maximum bid) calculated from thisfull model analysis was 1938.97 yen (approximately $19)
while the median was 1311.10 yen (approximately $13). On
the contrary, the full model regression analysis for inferredvalues (n = 122) revealed that seven independent variables
had a significant effect (Table 5). Respondents who received
financial support from their parents gave lower inferredvalues (B = − 1.106, p < 05), while respondents who did
part-time job (B = 0.892, p < 0.1), who were interested inusing renewable energy (B = 0.594, p < 0.05), using environmentally friendly goods (B = 0.506, p < 0.1), and eatingorganic vegetables (B = 0.398, p < 0.1) gave higher inferredvalues. Respondents in 2020 offered significantly higher
inferred value than those in 2016 (B = 0.956, p < 0.1). Similar to WTP, log (Bid) had significantly negative influence
on inferred value (B = − 2.337, p < 0.01). The mean inferredvalue (truncated at the maximum bid) calculated from thisfull model was 1170.48 yen ($11) while the median was
857.80 yen ($8). The model that estimated WTP fit better than the one that estimated inferred value indicated by
the high Log-likelihood value (− 261.806 for WTP and− 130.816 for inferred value).
As there were approximately 6,500 undergraduate students at the campus when this survey was conducted (nearly
1,600 at the College of Policy Science, nearly 3,500 at theCollege of Business Administration, and nearly 1,200 at theCollege of Comprehensive Psychology), the estimated utility value of implementing student-led agricultural activities,
based on median WTP values calculated from the pooled
2016 and 2020 samples, is as follows:Sustainability Science
Table 5  Factors affecting
individuals’ WTP and inferredvalues based on the full model
analysis using logit model
estimation (bold letters show
items that had significant effects
on WTP and/or inferred value)

Variables

WTP (n = 216)

Intercept
AgePart-time job
Financial support from parents
Interested in recycling
Interested in nature conservation on campusInterested in utilizing renewable energy
Interested in using environmentally friendly goods
I turn lights off as much as possible
I bring my own bag
I set low temperatures on heaters
Interested in growing my own vegetables
Interested in eating vegetables I have grown
Interested in eating organic vegetablesYear
Log(bid)Log-likelihood

Inferred value (n = 122)

Estimatez value

Estimatez value

10.932
0.017
0.387
0.011
− 0.256
0.0347**0.579***− 0.168
0.050***
0.211*− 0.203*
0.422**− 0.097− 0.0340.256− 2.021***− 261.806

8.517
0.075
1.076
0.036
− 1.3192.412
3.076− 0.8702.990
1.944− 1.7312.138− 0.456− 0.2270.759− 13.621

10.024− 0.308
0.892*− 1.106**− 0.100− 0.0280.594**
0.506*
0.181
0.140− 0.043
0.184− 0.3120.398*
0.956*− 2.337***− 130.816

5.525− 0.9621.673− 2.504− 0.386− 1.596
2.364
1.663
1.012
0.887
− 0.253
0.593− 0.9501.721
1.880− 10.047*Significant at the 10% level, **significant at the 5% level, ***significant at the 1% level1, 311.10 yen × 6, 500 (undergraduate students at the campus) × 0.295(response rate [those who showed intention to donate])()= 2, 514, 034.25 yen approximately $25, 100 .

Similarly, the estimated utility value for implementing student-led agricultural activities based on the medianinferred value is as follows:

857.80 yen × 6, 500 × 0.295(same response rate as WTP)()
= 1, 644, 831.5 yen approximately $16, 400 .

Discussion
Comparison of students’ perceptions
and demographic attributes in 2016 and 2020
By conducting a survey of students in the same college
within the same grade but in different years, we were able
to identify differences in their levels of environmental perceptions, degree of pro-environmental behaviors, and certain
demographic attributes. Most notably, students in 2020 had
significantly higher interests in engaging in pro-environmental behaviors and were more likely to engage in actual
behaviors than students surveyed in 2016.
The significant differences between students’ perceptions and behaviors in 2016 and 2020 could be explainedby the spread of ideas around environmental conservationand sustainability in Japanese society during these four
years. For example, since 1 July 2020, Japanese stores
have charged extra for plastic bags, which was a mandate
based on an amendment of the Containers and Packaging
Recycling Law. This encouraged consumers to bring theirown bags if they wanted to avoid paying for a bag. According to a recent survey, 87% of consumers currently taketheir own bags when they go shopping (Planet 2021). It
probably explains why students in 2020 were more likely
to bring their own bags when shopping than the students
surveyed in 2016.
Additionally, the Sustainable Development Goals (SDGs)
were declared by the United Nations in 2015; in Japan, thecabinet is attempting to stimulate public awareness of sustainability and pro-environmental behaviors (Kanie et al.
2019). Recent media analysis has revealed that the numberof newspaper articles explaining and promoting the SDGs
has rapidly increased over the years, and more sustainabilityrelated information in these media has the potential to significantly enhance citizens’ (and students’) environmental
awareness and behaviors (Sakurai et al. 2021). A survey conducted among Japanese university students in 2019 revealed
how the idea of SDGs has taken root; many students realized

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Sustainability Science

the importance of sustainability awareness and engaged inpro-environmental behaviors (Uehara and Sakurai 2021).
Moreover, the spread of COVID-19 and related lifestylechanges after the pandemic might have significantly affected
people’s (and students’) perceptions on environmental
issues. It has been pointed out by media and researchersthat the COVID-19 outbreak is linked to the destruction offorests (Tollefson 2020). We speculate that the COVID19 pandemic could have strengthened students’ perceived
importance of environmental conservation. For example,
previous studies have shown that students’ environmental
awareness toward sustainability and willingness to protect
the environment was enhanced after watching news about
COVID-19 (Uehara and Sakurai 2021). A previous study
that analyzed international survey datasets including theWorld Values Survey revealed how generalized trust (e.g.,
how much people trust others) could narrow the gap between
environmental concern and pro-environmental behavior(Tam and Chan 2018), and various factors including trustlevel should be explored and analyzed in the future study
to identify why students’ environmental concern changed
over four years.
Meanwhile, significantly more students had part-timejobs in 2020 than in 2016, which could also be caused by the
spread of COVID-19. Since all courses were taught online
in the spring semester of 2020, students had more free time
(as they did not need to commute to universities). For somecourses, instructors uploaded course materials online, andstudents could check and study them whenever they were
free without needing to attend synchronous lectures. This,in turn, gave students more flexible schedules, enabling themto engage in part-time jobs (Pustika 2020).

Comparison of WTP and inferred values in different
years
Students’ WTP for donations towards student-led agricultural activities was higher in 2020 than in 2016; both WTP
and inferred values were more than 700 yen larger in 2020.
Based on the fact that students in 2020 had higher interests
in engaging in pro-environmental behaviors, it is reasonable that their WTP for student-led agricultural activities,
which contribute to campus sustainability (e.g., by stimulating local production/consumption movements), is muchhigher in 2020. Several responses to open-ended questions
mentioned that creating such agricultural fields on campus
and starting agricultural activities is in line with the creationof a sustainable society.
The full model analysis revealed that several factors
related to awareness and pro-environmental behaviors significantly affected WTP values. Our findings demonstrate
how environmental awareness (e.g., energy saving) could
positively affect students’ WTP for creating a sustainable13

campus. Meanwhile, mean WTP for creating agricultural
fields in our research was 2376.8 yen, much smaller thanpublic WTP for nature conservation calculated from previous studies in Japan [7,173 yen for conservation of fish species (Oshida and Numata 2016), 10,574 yen for use valueof conservation area (Mori et al. 2013)]. While we cannot
simply compare our results with previous studies as respondents’ demographics are different, it can be assumed that people’s WTP for such topic as creation of agricultural fields
is generally lower than that of environmental conservation.
Contrary to our first hypothesis, the confidence intervalsof WTP and inferred values overlapped for both 2016 and2020, thus indicating that inferred values were not significantly lower than WTP. A previous study conducted among
the same university students revealed that students’ WTP
values were more than two times larger than inferred values
for donations towards an anti-smoking patrol on campus(Sakurai and Uehara 2017); in our study, WTP was approximately 1.5 times bigger than inferred values. Lusk and Norwood (2009) reported that topics triggering stronger social
desirability would result in higher WTP. Smoking is bannedon campus at the university where the survey was conducted;
it is also currently banned in most public areas in Japan, as
the negative effects of smoking on public health are widely
recognized (Inui 2007; Japanese Circulation Society 2016).
Therefore, it is possible that students were more likely tostate a higher WTP value compared to the inferred value forquestions regarding smoking (Sakurai and Uehara 2017).
Compared to the theme of smoking, which is officiallybanned, students would be less criticized for not supporting
student-led agricultural activities. This phenomenon could
have affected the results, thus yielding non-significant differences between WTP and inferred values. Previous studies
on protection of nature or at-risk species all showed morethan twice the difference between WTP and inferred value(Lopez-Becerra and Alcon 2021; Entem et al. 2022) implying that creation of agricultural fields is a topic that generates less social desirability bias than nature conservation.
Nonetheless, even for the non-controversial topic of studentled agricultural activities, our results showed much smaller
inferred values than WTP, following previous studies (Lusk
and Norwood 2009; Tanaka and Nagahiro 2019). It demonstrates that inferred values could yield more conservativeand potentially realistic estimates than conventional WTP
for various aspects of environmental valuation.
Years did not affect students’ WTP while they affected
inferred values in the full model regression analysis, implying that our second hypothesis—students’ WTP and inferredvalues for the same service would be identical in different
years—was partially supported. This was also in line withthe previous study that showed local residents’ WTP forcoastal conservation projects did not significantly changeover 17 years (Uehara et al. 2018), although the global value

Sustainability Scienceof ecosystem services more than doubled due to loss of ecoservices over years (Costanza et al. 2014).
Using median values (which generally represent moreconservative scores than the mean), the total utility value ofcreating a student-led agricultural association was more than
2.51 million yen (approximately $22,700). Approximately
300,000 yen (nearly $2,800) is necessary for preparing basic
agricultural equipment (e.g., mowers, cultivators) and seeds
for cultivating a small agricultural field (e.g., 10 m × 30 m).
Subtracting 300,000 yen for buying necessary equipment
and goods, more than 2 million yen (approximately $18,000)
could be used for recruiting students to manage the agricultural fields. Based on the mean hourly part-time wage inOsaka prefecture (1,000 yen/hour; Osaka City 2021), hiring
a student to work 4 h a day for 10 days a month would cost
40,000 yen. It means that 480,000 yen (nearly $4,000) is
required annually to hire a student to manage the agricultural
field. Therefore, our results imply that donations by students
would facilitate the hiring of more than four students a year.
If we use the inferred value (1.64 million yen), two students
could be hired. It shows that creating on campus studentled agricultural associations and implementing agriculturalactivities at our study site is economically feasible via students’ donations.
As one of the first studies to reveal potential factors
affecting inferred values, our goal was to reveal any factorsthat affect people’s valuations. However, a limitation of thisstudy is that we were not able to delve into the reasons on
why certain factors affect WTP, especially inferred value.
Future research should investigate why certain factors affectinferred value, i.e., the mechanism by which people value
other people’s WTP should be investigated.

Conclusion
Our study revealed that inferred value could identify moreconservative and realistic estimates of students’ donation
than conventional WTP. Even using the inferred value, thisstudy showed that student-led agricultural activities arefinancially feasible through student donation. Recognizing
the importance of creating sustainable campuses, various
efforts are made to start agricultural activities in schools
and universities all over the world (Pevec et al. 2017, KASA
Sustainability n.d.). Based on the results of our study, we
propose policy suggestions for creating sustainable campuses. In order to realize such participatory sustainablecampuses, willingness to support such projects by students
and other stakeholders should be identified. When revealing

their willingness to devote financially, not only WTP but
their inferred value should be measured to obtain more conservative estimation avoiding social desirability bias. Oncesuch financial value, potential donation amount, is identified,universities can let students and other stakeholders start theirown organization to build such environmentally friendly
campuses, and donation could be asked and collected.

Appendix 1 Grade and age of students
Frequency (%)

Frequency (%)

2016
2020
(n = 365) (n = 337)

2016
2020
(n = 361) (n = 336)

GradeFirst 341 (93.4)337 (100)Age 18
year
Second 8 (2.2) 0 (0)19year
Third 9 (2.5) 0 (0)20
year
Fourth 5 (1.4) 0 (0)
21
year
More
Over 2 (0.5) 0 (0)
than
fifth
22
year

282
186 (55.4)(78.4)
55 (15.1) 129 (38.4)
12 (3.3) 17 (5.1)
8 (2.2)3 (0.9)4 (1.1)1 (0.3)

Data availability The anonymized data presented in this study areavailable on request from the corresponding author.

Declarations
Conflict of interest The authors received no direct funding for this research. No potential conflict of interest was reported by the authors.
Before each survey, the authors explained the contents and objectivesof this research. Furthermore, the anonymity of all the data obtained
was ensured. Participants were informed that their participation was
voluntary. The survey was distributed once the author obtained informed consent from all the participants.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as longas you give appropriate credit to the original author(s) and the source,
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article areincluded in the article's Creative Commons licence, unless indicatedotherwise in a credit line to the material. If material is not included in
the article's Creative Commons licence and your intended use is not
permitted by statutory regulation or exceeds the permitted use, you willneed to obtain permission directly from the copyright holder. To view acopy of this licence, visit http://​creat​iveco​mmons.​org/​licen​ses/​by/4.​0/.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as longas you give appropriate credit to the original author(s) and the source,

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Sustainability Science
provide a link to the Creative Commons licence, and indicate if changes
were made. The images or other third party material in this article areincluded in the article’s Creative Commons licence, unless indicatedotherwise in a credit line to the material. If material is not included in
the article’s Creative Commons licence and your intended use is not
permitted by statutory regulation or exceeds the permitted use, you willneed to obtain permission directly from the copyright holder. To view acopy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

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