GCOE Discussion Paper Series
Global COE Program

Human Behavior and Socioeconomic Dynamics
Discussion Paper No.70

Do Consumers Select Food Products Basedon Carbon Dioxide Emissions?
Evidence from a Buying Experiment in Japan

Keiko Aoki

July 2009; revised January 2011

GCOE Secretariat
Graduate School of Economics

OSAKA UNIVERSITY

1-7 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan

Do Consumers Select Food Products Based on Carbon Dioxide Emissions?
Evidence from a Buying Experiment in Japan
Keiko Aoki ∗Institute of Social and Economic Research, Osaka University

Abstract
This study investigates whether consumers select foods based on the levels of carbon dioxide (CO2)emissions by using a choice experiment in the laboratory. Respondents are asked to purchase a few
Satsuma mandarin oranges based on price and the levels of CO2 emissions during different stages of
their life cycle of production until packing and to answer questions on environmental consciousness,knowledge, and behavior. The following results are obtained: (i) the result for the high and lowgroups with respect to environmental consciousness is only significant different. (ii) the willingness
to pay (WTP) estimate for the reduction of 1g of CO2 emissions per Satsuma mandarin orange issignificantly lower for the low environmentally conscious group than it is for the highenvironmentally conscious group; (iii) the choice reasons selected by the respondents indicate thatthe low environmentally conscious group is less likely to select foods based on their CO2 emissions,whereas the high environmentally conscious group is indifferent to both price and the levels of CO2
emissions; and (iv) socioeconomic characteristics such as gender, age, and education influence theselection of foods on the basis of CO2 emissions in the low environmentally conscious group.
However, this is not the case in the high environmentally conscious group. Therefore, this study
implies that regardless of consumers’ environmental knowledge and behavior, the higher theirenvironmental consciousness, the greater their likelihood of selecting foods with lower
environmental loads.
Key words: carbon dioxide emissions, choice experiment, consumer preference, food choice,laboratory experiment, random parameter logit∗

E-mail: k_aoki@iser.osaka-u.ac.jp, Institute of Social and Economic Research, Osaka University,

6-1 Mihogaoka, Ibaragi, Osaka 567-0047, Japan1

1. Introduction
A number of labels affixed on foods indicate the nutrition levels of their ingredients in terms ofcalories. Recently, under the protection of the Kyoto Protocol in 1997, new eco-labels have begun
appearing on foods though the eco-label was previously affixed only on non-foods (e.g., cars,
household appliances, etc.); this protocol mandates that in 2008–2012, some developed countries
must reduce greenhouse gas (GHG) emissions by at least 5% as compared to that in 1990. Since theeco-label on a non-food product indicates that it has the merits of being economical and low runningcost, consumers purchasing non-foods attribute importance to whether or not the eco-label is affixed
on the product. As a result, some consumers increasingly select those non-foods that possess labels
indicating low environmental load. With respect to studies on eco-labeling, empirical analyses(Wessells et al., 1999; Johnston et al., 2001; Teisl et al., 2002; Bjørner et al., 2004; OECD, 2005;
Teisl et al., 2008; Brécard et al., 2009) 1 , theoretical models (Kirchhoff, 2000; Amacher et al., 2004;
Hamilton and Zilberman, 2006; Ibanez and Grolleau, 2008), and experimental methods (Cason andGangadharan, 2002) have all indicated that eco-labeling has positive effects on the purchasing
behavior of the consumer, respectively. Moreover, the environmental factors such as environmental
attitudes, knowledge, and behavior are more likely to influence socioeconomic characteristics(Diamantopoulosa et al., 2003). 2
A new kind of label for foods indicates environmental information in terms of the amountof CO2 emissions (e.g., carbon footprint 3 , carbon offset 4 , food miles 5 ) 6 as well as the biologically
productive land and sea area (e.g., ecological footprint 7 ). However, these labels do not have the same
merits as them for non-foods. Moreover, foods with a lower environmental load do not always taste
better as compared to those with a higher environmental load. Therefore, the knowledge of whether
consumers attribute higher value to foods with a lower environmental load is important for producers
who may introduce their foods with labels and to policy makers who would design an environmental
policy. The abovementioned studies may enable producers and policy makers to anticipate whether
consumers attribute a higher value to foods with eco-labels. The following studies on food would
further enable them to anticipate whether they distinguish between foods with lower and higher
environment loads: Roe and Teisl (2007) investigate consumer reactions to labels that have written
1

Wessells et al. (1999), Johnston et al. (2001), Teisl et al. (2002), and Brécard et al. (2009) used seafood products.
Bjørner et al. (2004) used toilet paper, paper towels, and detergents. Teisl et al. (2008) used “greener” vehicles.
2
Diamantopoulosa et al. documented the following as the components of environmental consciousness: attitudes
towards environmental quality, knowledge regarding green issues, and levels of environmentally sensitive behavior.
They conducted interviews and surveys by mail in the UK.
3
For more details on carbon footprint and Carbon Trust, refer to Wiedmann and Minx (2008) andhttp://www.carbon-label.com/, respectively.
4
For more details on carbon offset, refer to the Carbon Neutral Company site (http://www.carbonneutral.com/).
5
For more details on food miles, see Hill (2008).
6
The amount of CO2 emissions is calculated by several sites as indicated in Kim and Neff (2009).
7
For more details on the ecological footprint, see the Global Footprint Network site(http://www.footprintnetwork.org/en/index.php/GFN/).

2

information on the presence and potential effects of genetically modified (GM) food ingredients andabout the agencies that certify these claims by using a mail survey. They indicated that consumers
prefer simple GM labels to no GM labels and that although the adequacy of a simple GM label isenhanced if the label comprises the reason for using GM techniques, the addition of this reason in
the label significantly erodes the label’s credibility ratings. Bernings et al. (2010) investigate shopper
preferences for nutritional information provided on grocery store shelf labels by using a choice
experiment and concluded that this information influenced consumers since they are more likely toseek healthier items instead of those items without any shelf label information. However, producers
and policy makers cannot anticipate whether consumers select foods based on environmental factors
such as the levels of CO2 emissions or on the price and foods characteristics such as appearance andtaste. Hence, consumer behavior on food choices must be investigated under the real conditions thatthey actually purchase foods based on price, environment indicator such as CO2 emissions, and theappearance of foods and analyzed using environmental factors such as environmental consciousness,knowledge and behavior.
This study investigates whether consumers select Satsuma mandarin oranges (Citrus
unshiu Marc.), which is the most representative fruit of Japan, by conducting a non-hypotheticalchoice experiment (CE) in the laboratory. The respondents were provided with the price andinformation on the levels of CO2 emissions based on the life cycle inventory of this type of orange,
and they were asked to purchase them in 12 rounds. After each round, they selected the reason for
their choice from among the following four factors: price, CO2 emissions, appearance, and others. At
the end of the experiment, the respondents were asked to answer three types of questionnaires
regarding environmental factors (i.e., environmental consciousness using a psychological scale,environmental knowledge of eco-labels, and environmental behavior, which respondents exhibit indaily life). Finally, the respondents could take the earnings and the oranges that they had selected ineach round. Similar to this study, Alfnes et al. (2006) designed an experimental market with posted
prices and used the CE for investigating consumers’ willingness to pay (WTP) for the color of
salmon fillets. They demonstrated that consumers use color as a quality indicator of salmon and arewilling to pay significantly more for salmon fillets with normal or above-normal redness than for
paler salmon fillets, which implies that color influences consumer preferences.
The CE approach used in this study is a type of stated preference method (Louviere, 2000)
such as the contingent valuation method and the conjoint analysis, which is a measure of theconsumer’s preference elicitation to non-market goods (e.g., environment goods, health risk). 8
Moreover, the CE approach is useful for effectively overcoming certain biases (e.g., strategic bias,

8

Although the second-price sealed-bid auction is also a measure of preference elicitation, we used the CE methods
in this study because we focused on consumers’ choice behaviors in conditions that were as close to the realconditions as possible.

3

compliance bias, and warm glow bias) 9 , which the data in the contingent valuation method usuallypossesses; this is because the translation of the commodities’ features into attributes permits analysts
to assess the effect of a change in the objective properties of commodities. Moreover, a hypotheticalcondition in the CE also possesses a hypothetical bias such that the WTP under this condition ismore than that under a real condition (Kurse and Thompson, 2003; Lusk and Schroeder, 2004;
Harrison and Rutström, 2008; Chang et al., 2009; Aoki et al., 2010). Therefore, the WTP must be
investigated by using the CE under real conditions. Although field studies have the obvious
advantage of creating a more natural environment and in increasing a sample, the real condition inthis study uses experimental methods with monetary incentives. This is because these methods canclearly indicate the factors that influence consumers’ preference for foods providing information
regarding CO2 emissions and why consumers prefer such foods as compared to those that do notprovide this information.
The remaining paper is organized in the following manner: Section 2 explains theexperimental design and procedure. Section 3 describes the empirical model structure. Section 4
presents the results, and Section 5 indicates the conclusions.

2. Experimental design and procedure

2.1. Design
We conducted a laboratory experiment based on the CE method. As indicated in Appendix A, thethree alternatives in the designated choice sets were Satsuma mandarin oranges A, B, and C. 10
Satsuma mandarin oranges 11 were used in this study for the following reasons: First, Satsuma
mandarin oranges are the leading fruit in Japan in terms of production and consumption. Therefore,
the respondents ought to be familiar with this product. Second, these oranges do not require
additional CO2 emissions because they can be eaten directly without cooking or using any othertools. Third, since the period of the experiment corresponds to that when oranges are in season, it islikely that it is easy for respondents to remember the taste of the oranges even though they do not eat
them during the experiment.
The attributes being tested in each round of this study were the price and the CO2 emission
9

For more details on this issue, see Louviere et al. (2000).
In the study, the alternative of “no purchase” does not exist because our purpose is to test whether consumers
select foods based on the levels of CO2 emissions; the frequency of individuals selecting foods on this basis wasfound to be greater under the real condition (Lusk and Schroeder, 2004).
11
We used the goku-wase, a type of Satsuma mandarin orange, in this study. Each Satsuma mandarin orange wasapproximately 7 cm in diameter, and its weight was approximately 100g. We purchased the Satsuma mandarinoranges from three different prefectures (i.e., Wakayama, Ehime, and Kumamoto) and the largest quantities of theseoranges are available11 at supermarkets and stores in these areas. Its color was orange with a bluish tinge. As
compared to other types of Satsuma mandarin oranges, the taste of these oranges was sour. The sugar content in them10

was approximately 9−11 brix. For more details on Satsuma mandarin oranges, see Morton (1987).

4levels. 12 The levels of the price attribute were JPY 25, 35, and 45 per Satsuma mandarin orange.
These levels were based on the prices of Satsuma mandarin oranges in the three largest supermarkets
in the area and on the data obtained from the Statistical Bureau in the Ministry of Internal Affairs
and Communications. 13 The levels of the CO2 emissions attribute were 20g, 30g, and 40g per
Satsuma mandarin orange. These levels were based on the life cycle assessment (LCA) because it
was found that the amounts of the CO2 emitted in the LCA process differed for different foodproducts. The LCA in this study comprised the following four stages: production, fruit sorting andbox packing, transportation, and packaging. 14 Table 1 shows the CO2 emissions calculated in eachprocess. 15 Therefore, a full factorial design with three prices and three CO2 emissions levels would
have resulted in 729 alternative management combinations. Since this would constitute an
unreasonably large design in practice, a D-optimal fractional factorial design with 24 alternatives
was developed and separated into two blocks of 12 choice sets by using Design Expert (version 7).
------------------------------Table 1 is around here------------------------------In order to evaluate the effect of the following environmental factors on consumers’purchase decisions, the questionnaire consisted of three types of questions regarding theenvironment, as indicated in Appendix B: (i) environmental consciousness (hereafter EC), which isestimated using a psychological scale and indicates the ecologically conscious consumer behavior(Roberts, 1996). In this study, the effect of this factor is estimated on the basis of 10 questions thatare designed for assessing the consumers’ ecological purchase behaviors by asking respondents torate the veracity of various statements with respect to their purchase behavior and its connection toenvironmental product attributes; (ii) environmental knowledge of eco-labels (hereafter EK), theeffect of which is estimated by asking respondents to identify 24 eco-labels that aid the purchase ofenvironmentally friendly goods and 11 eco-labels that serve as identifying marks in Japan 16 ; and (iii)
environmental behavior in daily life (hereafter EB), the effect of which is estimated using six
questions that evaluate consumer’s behaviors in daily life and otherwise.

12

The appearance was used in the choice reasons and not the attributes because it is subjectivized by individuals.
This data indicates the prices of the Satsuma mandarin oranges that were sold at all the supermarkets and shops inJapan. We selected the prices from the available price data for the Osaka prefecture.
14
In this study, we do not add the levels of CO2 emissions of oranges during their sale in supermarkets and stores
because a number of other goods are present there.
15
This was referred to by Nemoto (2007).
16
They are selected from the database of the Ministry of the Environment(http://www.env.go.jp/policy/hozen/green/ecolabel/f01.html).
135

2.2. Procedure
The following is the detailed procedure of the experiment:
Step 1: One of the experimenters read aloud a consent form at the beginning of the experiment. The
consent form stated that the respondents would have to purchase Satsuma mandarin oranges
12 times and that they had the right to withdraw from the experiment at any time if they did
not wish to make these purchases. 17
Step 2: An experimenter explained aloud the experimental procedure to the respondents after theexperimental instruction sheets were distributed. 18
Step 3: At the beginning of the round, the respondents received 120 JPY as endowment in order topurchase one Satsuma mandarin orange from among the three types of oranges that were
kept in a box. 19 Subsequently, they were asked to select one of the oranges kept in front ofthem and to select one of the reasons for their choice.
Step 4: Step 3 was repeated until the 12 rounds were completed.
Step 5: After round 12, the respondents were asked to complete a questionnaire that evaluated theirsocioeconomic characteristics and the effects that environmental factors such as EC, EK,
and EB had on their purchase decisions.
Step 6: The respondents received a show-up fee (500 JPY) and their earnings in each round in cash.
The earnings were calculated by subtracting the price of the Satsuma mandarin orange thatthe respondents purchased from the amount they received for purchasing the oranges (120
JPY). Moreover, the respondents could take home the 12 Satsuma mandarin oranges thatthey had selected in each round. 20

3. Model structure
In this study, we use the conditional logit model (CL) as well as the random parameter logit model(RPL) for analyzing the data samples. Both these models are based on the random utility theory,
which is central to the concept of choice modeling. The basic assumption underlying the random
utility approach to choice modeling is that decision makers are utility maximizers, which implies

17

A consent form was provided to every respondent during recruitment. The respondents were asked to read it
carefully before participating in the experiment. All the respondents signed the form and none of the respondents
dropped out of the experiment.
18
The instructions for the experiment are provided in Appendix C.
19
The order of the oranges in the box is based on the CO2 emissions in each alternative, which correspond with theprefectures producing them as indicated in Table 1.
20
The respondents take home the oranges selected by them on the basis of the CO2 emission levels in each roundwhere the CO2 emission levels of 20g, 30g, and 40g correspond to oranges from Wakayama, Ehime, and Kumamoto,respectively. However, two male respondents did not take the oranges home.

6that given a set of alternatives, decision makers select the alternative that maximize their utility. The
utility of an alternative for an individual (U) cannot be observed; however, it may be assumed toconsist of a deterministic (observable) component (V) and a random error (unobservable) component( ε ). Formally, an individual q’s utility of alternative i can be expressed as U iq = Viq + ε iq . Hence, theprobability that individual q selects alternative i from a particular set J, which comprises jalternatives, may be expressed as follows:
Piq = P(U iq > U jq ; for all j (≠i ) ∈J ) = P(ε jq < ε iq + Viq - V jq ; for all j (≠i ) ∈J )(1)

In order to transform the random utility model into a choice model, certain assumptions regarding
the joint distribution of the vector of random error components are required. If the random error
components are assumed to follow the type I extreme value (EV1) distribution and to be
independently and identically distributed (IID) across alternatives and cases (or observations), a CLmodel (McFadden, 1974) can be obtained. Assuming that the deterministic component of utility in
the CL model is linear and additive in parameters, Viq = β ′Χ iq , the probability in Equation (1) may
be expressed as follows:

Piq ( β q′ ) =exp( μ β ′Χ iq )
J

∑

,

(2)

exp( μ β ′Χ jq )j =1

where μ represents a scale parameter that determines the scale of the utility, which is proportional
to the inverse of the distribution of the error components and is typically normalized to 1.0 in theconditional model.

Χ iqdenotes the explanatory variables of Viq , typically including

alternative-specific constants (ASCs) of the attributes of alternative i and socioeconomic
characteristics of individual q, and β ′ is the parameter vector associated with matrix Χ iq .
However, the CL model is also limited in that it assumes all respondents share the same
parameters for the attributes, thereby implicitly assuming that there is homogeneity of preferences
across all the respondents sampled. Moreover, the CL model assumes the independence of irrelevantalternatives (IIA) property. 21 If the IIA property is violated, the results of the CL model will bebiased. This implies that a discrete choice model that does not require the IIA property, such as the
RPL model (Train, 1998, 2003), must be employed. In contrast with the CL model, since thecoefficients in the RPL model vary among respondents, the utility that an individual q derives fromselecting alternative i on choice set t may be expressed as U iqt = Viqt + ε iqt = β q′ X iqt + ε iqt . The densityfor β q′ is denoted as f ( β | θ ) , where θ is a vector of the true parameters of the taste distribution.
The conditional probability of alternative i for individual q in choice set t is expressed as follows:21

The IIA property states that the relative probabilities of two options being selected are unaffected by the
introduction or removal of other alternatives.

7

Piqt ( β q′ ) =exp( β q′ X iqt )
J

∑

,

(3)

exp( β q′ X jqt )j =1

The probability of the observed sequence of choices conditional on knowing β q′ is expressed asfollows:
T∏P

S q ( β q′ ) =qi ( q ,t ) t( β q′ ),

(4)

t =1

where i (q, t) represents the alternative selected by individual q on choice set t. The unconditional
probability of the observed sequence of choices for individual q is the integral of the conditional
probability in Equation (4) over all possible variables of β ′ and can be expressed as follows:∫

Pq ( θ ) = S q ( β ) f ( β | θ )dβ .

(5)In most applications, the density f ( β | θ ) has been specified to be normal or lognormal:

β ~ N ( b ,W ) or ln β ~ N ( b ,W ) with mean, b, and covariance, W, are estimated. 22 In this study, we
use normal density.
Based on the above discussions, the main effect in Model 1 is estimated using the CL andthe RPL models because of the result obtained in the Housman test. 23 Further, the main effect inModel 2 is estimated using the RPL model for the analysis with socioeconomic characteristics in two
indirect utility functions as below.
Model 1: Viq = β 1PRICEi + β 2 CDEi ,Model 2: Viq = β 1PRICEi + β 2 CDEi +K∑δ CDE × SOCIO ,
k

i

kq

k =1

where PRICEi is the price level of Satsuma mandarin orange i, CDEi is the CO2 emission levelof Satsuma mandarin orange i, and CDEi × SOCIOkq is the interaction term of the CO2 emission
level of Satsuma mandarin orange i with a dummy variable indicating the socioeconomic
characteristics k of individual q. β1 , β 2 , and δ k are parameters that are to be estimated.
4. Results
We conducted the laboratory experiment at the Osaka University. The respondents were recruitedfrom the Osaka University campus and from among the neighborhood residents from a randomly
selected sample of 5,700 households around the university. We recruited student and non-student
22

There are other densities specified as triangular, uniform, and Rayleigh distributions. See Train (2003) (pp.142)
and Hensher and Greene (2003).
23
In this study, the Hausman test for the independence of irrelevant alternatives (IIA) property (Hausman and
McFadden, 1984) provided that the IIA property cannot be rejected only in the case where alternative C is dropped(chi-square (2) = 430.842, p-value = 0.000) (The following are the other results: if alternative A is dropped(chi-square (2) = 0.570, p-value = 0.752), and if alternative B is dropped (chi-square (2) = 2.597, p-value = 0.273)).

8

subjects in order to include members from different socio-economic backgrounds rather than only
student subjects. Student subjects were recruited by leaflets on-campus advertisements. Non-student
subjects were recruited by advertising the survey through leaflets inserted in four kinds of Japanesenewspapers. 24 We conducted 15 sessions with 104 respondents (63 residents and 41 students) during
November 4−9, 2008. 25 Each respondent was permitted to participate in only one experimental
session. On an average, each respondent earned 1,407 JPY. Each session lasted for approximately 60
minutes.
Here, in order to investigate which environmental factors consumers are influenced when
they select the oranges based on the levels of CO2 emissions, we will employ the results of the threeenvironmental factors, i.e., EC, EK, and EB, used in the questionnaire. First, the Spearman rankcorrelation coefficients between EC and EK and those between EC and EB were 0.147 (p-value =0.000) and 0.282 (p-value = 0.000), respectively. Second, the raw data for each environmental factor
was divided into the following two groups: the high group, which consisted of respondents whose
responses were more than the average synthesis scales in EC and the average number in EK and EB,
and the low group, which consisted of the other respondents in each factor. 26 The results of the LRtest only indicate significant differences between the high and low groups for the EC factor(chi-square(2) = -2(-1107.579 -(-545.375-550.912)) = 22.585, p = 0.000)) at the 5% significant
level. 27 . Therefore, since EC bears a more significant influence on consumers’ selection of oranges
based on the CO2 emissions, the results will be analyzed for these two groups only for the EC factor.
Table 2 shows the results of Model 1, which employs the CL and the RPL models, andModel 2, which employs the RPL model with interactions, for the high and low environmentallyconscious groups by using LIMDEP 9.0 NLOGIT 4.0. Here, we use a simulated maximum
likelihood estimator in order to estimate the models by employing Halton draws with 100
replications (Revelt and Train, 1998; Train, 2000). The variable CDE is specified to be normally
distributed (Revelt and Train, 1998; Train, 1998; Carlsson et al., 2003). The estimates of the twovariables, Price and CDE, indicated significant and negative signs for both the groups, implying that
all the respondents preferred to purchase Satsuma mandarin oranges that were cheaper 28 and emitted

24

The newspapers are Mainichi, Asahi, Yomiuri, and Sankei which are major ones in Japan.
The socioeconomic characteristics of the respondents in the experiment are summarized in Appendix D.
26
In the EC, a synthesis scale aggregates the scales of all the questions. This scale’s Cronbach’s alpha reliability
coefficient is 0.839. Therefore, the two groups under EC are defined as the high group, which consists of respondents
whose responses are more than the average synthesis scale of 30, and the low group, which comprises the other
respondents. In the EK, the high group includes respondents whose responses are more than the average number of 11.
In the EB, the high group includes respondents whose responses are more than the average number of three; question
7 is excluded.
27
In CL model also, the results were the same as that of the RPL model (chi-square (2) = -2(-1111.141 - (-547.243 552.238)) = 23.320, p = 0.000). The results of the LR test indicate insignificant for the EK (chi-square(2) =-2(-1107.579-(-553.503-551.755)) = 4.642, p = 0.098) and the EB factors (chi-square(2) = -2(-1107.579 -(-638.925-466.853)) = 3.602, p = 0.165), respectively.
28
The result of cheaper purchases supports Prescott et al. (2002), which indicated that Japanese consumers
particularly ascribed value to price.
25

9

lower levels of CO2 regardless of the degree of EC. However, the marginal WTP estimate for the
reduction of 1g of CO2 emission per Satsuma mandarin orange in the low environmentally conscious
group was lesser than that in the high environmentally conscious group. This implies that the higher
the environmental consciousness, the more people may value foods that emit lesser CO2.
Subsequently, with respect to Model 2, which uses the RPL model with interactions, noneof the variables except the attributes in the high environmentally conscious group are significant.
However, in the low environmentally conscious group, the three variables CDE × Female,

CDE × Old, and CDE × University were estimated to have significant, negative, and positive signs,
respectively. This implies that female respondents attribute greater value to CO2 emissions ascompared to male respondents, which supports the findings in Wessells et al. (1999),
Diamantopoulosa et al. (2003), Teisl et al. (2008), and Brécard et al. (2009). 29 Further, it implies thatyounger respondents attribute greater value to CO2 emissions as compared to older respondents,
which does not support the findings in Moon et al. (2002), 30 and that high school educatedrespondents attribute greater value to CO2 emissions as compared to university educated respondents,
which support the finding in Johnston et al. (2001) but not that in Teisl et al. (2008) 31 . Therefore,
although the preferences of the high group are more likely to be the same regardless ofsocioeconomics characteristics, those of the low group may differ.
Here, the results of the two environmentally conscious groups, as indicated above, mayalso indicate the results of the choice reasons in each choice set. Table 3 shows the average numberof times a particular choice reason has been selected and the results of the Freidman test for the twoenvironmentally conscious groups. Similar to the results of the LR test, the Mann-Whitney U tests
indicated significant differences between the reasons provided by the high and the low groups withrespect to the choice reasons at the 1% significance level. 32 Since the Friedman rank sum test
initially indicates significant differences between the choice reasons in both high (chi-squared =13.192, p = 0.001) and low groups (chi-square = 35.106, p = 0.000), we will analyze which reasons
there are significant different. The Friedman test indicates that there is a significant difference
between “Appearance” and other reasons in the low group and between “CDE” and other reasons in
the high group. 33 These results imply that the respondents in the low group ascribed lesser value toCO2 emissions as compared to price and appearance, and that the respondents in the high group
29

They found that females tend to possess and exhibit better knowledge and behavior regarding green issues thanmales.
30
They found that older individuals consider environmental information more credible.
31
Although Johnston et al. (2001) found that more educated individuals do not necessarily ascribe greater
importance to environmental information, Teisl et al’s (2008) results were contrary to this finding.
32
The results of the Freidman test show in the choice reasons “Appearance” (z-statistics = -4.392, p = 0.000),“Price” (z-statistics = 20.665, p = 0.000), and “CDE” (z-statistics = -17.807, p = 0.000), respectively.
33
Similar to other multiple comparison tests, Tukye’s test for the comparison of the mean values also indicatessignificant differences between the choice reasons in the high group (Appearance vs. Price (t = 6.995, p = 0.000) andAppearance vs. CDE (t = 7.286, p = 0.000)) and the low group (Appearance vs. CDE (chi-square = 10.362, p =0.000) and Price vs. CDE (chi-square = 9.965, p = 0.000)).

10

ascribed greater value to appearance and are indifferent to price and CO2 emissions. Hence, thedifferences between the high and low groups in the EC category will influence the food choice
behavior when consumers select foods based on their levels of CO2 emissions.
-----------------------------------------Tables 2 and 3 are around here------------------------------------------

5. Conclusions
This study investigates whether consumers ascribe greater importance to CO2 emission levels overthe prices and appearances of oranges while purchasing them. The results indicate that respondents
with low environmental consciousness ascribe lesser value to selecting oranges based on their CO2
emission levels and that the socioeconomic characteristics of such respondents differ from thosewith high environmental consciousness who are indifferent to the price and CO2 emission levels oforanges. However, it was found that respondents ascribe value to appearance regardless of thedegree of their EC, which finding supports that of Bougherara and Combris (2009) who indicatedthat consumers ascribe greater importance to food characteristics such as taste or appearance ascompared to environmental protection. 34 Hence, these results in our study imply that the increasing
the level of environmental consciousness may enable consumers to select foods with low
environmental load.
The introduction of attaching new labels to foods as well as non-foods across the world
has facilitated the process of including everyday commodities for increasing environmental
consciousness. This is rather advantageous for reducing the amount of CO2 emissions in
consumer-oriented sectors such as the residential sector as well as the commercial sectors. However,producers and policy makers must consider the following two points for increasing consumer’s
environmental consciousness for foods with the help of these new labels. First is the different
degrees of environmental consciousnesses of individuals as indicated in this study. There is an
example as the change environmental consciousnesses of individuals over time: Grankvist and Biel(2007) investigated consumers’ foods choice behaviors for identifying the importance ascribed toenvironmental consequences by conducting a mail survey over a period of 18 months and found thatthe relative purchase frequency of consumers who had initially reported that they had never34

Bougherara and Combris (2009) employed the Becker–DeGroot–Marschak (BDM) procedure involving realtransactions for investigating whether the premium consumers who are willing to pay for eco-labeled orange juice are
driven by selfish or altruistic motives. This study specified that the eco-label on the product indicated that the productis organic and that the agricultural technique contributes to environmental protection. Moreover, the subjects whopurchased the orange juice could take it home. They found that consumers’ willingness to pay for the eco-labeledorange juice does not result from a perception of better taste or higher safety attributes, but from the desire tocontribute to public good for purely altruistic reasons, or selfish motives other than food taste or safety.

11

purchased eco-labeled foods subsequently increased according to environmental consequences andthat they had purchased them before, however, started to purchase based on eco-labelled productcharacteristics such as taste and price. Second is the difference among geographical conditions suchas the area and climate of different countries, which has not been studied here. For example, thedegree of self-sufficiency of a country influences the residents’ food purchases. Since the degree ofself-sufficiency in Japan is low, consumers always find foreign foods in supermarkets and shops.
Foreign foods emit higher amounts of CO2 but are cheaper than domestic foods. As a result, a few
consumers purchase them owing to its lower price and regardless of its influence on the environment.
Since consumers’ food choice behaviors also depend on the country characteristics, producers andthe policy makers in the countries with low degrees of self-sufficiency must prudently employ thesame methods that are successful in countries with a high degree of self-sufficiency.
This study suggests two possible directions for further research. First, since the sensory
information obtained from the process of eating a food product influences consumer behavior morethan other types of information (Prescott and Young, 2002; Aoki et al., 2010), it is essential tocompare the taste and/or nutrition of a food product with the consumer’s environmental
consciousness. Second, in order to increase the validity of the estimates, the WTP must be comparedwith those obtained by the other methods because the data in the CE possesses a starting point bias
(Ladenburg and Olsen, 2008). However, the existence of this bias is not supported in all the studies;
Ohler et al. (2000) and Hanley et al. (2005) found the starting point bias even though the price vector
changed, whereas the findings of Carlsson and Martinsson (2007) and Ryan and Wordsworth (2000)
indicated the opposite.

Acknowledgements
We would like to acknowledge the financial support provided by Grant-in-Aid for JSPS Fellows andby the Japanese Ministry of Education, Culture, Sports, Science and Technology (the Global COE
Program of Human Behavior and Socioeconomics Dynamics). We would also like to thank Takahiro
Tsuge for helpful advices in 2009 Japanese Econoimcs Association Spring Meeting, participants in
ESA European Meeting 2009, Kenju Akai, Mototsugu Fukushige, Masaru Sasaki, and Fumio Ohtake
for their helpful suggestions. The assistance of Kenta Onoshiro and Xiaoyan Yu in conducting theexperiment is also greatly valued.

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15

Table 1. The CO2 emissions based on life cycle inventory
Total CO2 emissions
Prefecture(g/ a Satsuma

Fruit sortingaProducts

and boxTransportationc

Packagingd

Packingb

mandarin orange)
Wakayama

23.192

16.295Ehime

32.26820.391

1.587
0.402

6.570

4.716

Kumamoto
34.304
16.59112.402aNote: quotes from the data in National Institute of Agro-Environmental Sciences (see:)(i.e.,
360–370 g-CO2/10 a) and Ministry of Agriculture, Forestry and Fisheries (see: In our study, the CO2
emissions level is approximately 365 g-CO2/10 a and the annual yield in Satsuma mandarin oranges
in Wakayama, Ehime, and Kumamoto are, 2,240,000, 1,790,000; and 2,260,000 g per 10 a,respectively. We calculate the CO2 emissions per a Satsuma mandarin orange.
bquotes from data in Nemoto (2007).
c
is based on data obtained from the Ministry of Land, Infrastructure and Transport. We calculate theCO2 emissions from each prefecture from where the oranges are obtained to the supermarket in thearea via Osaka prefecture central wholesale market by track. A lot of food products are collected inthis market and sent to supermarkets and stores. The running distance is calculated using a searchingroute by car on the Nippon Oil Corporation sitedis based on the Ajinomoto Group LC-CO2 emissions factor database for food related materials(1990, 1995, and 2000 editions; 3 EID compliant (Ajinomoto Co., Inc.). We calculate the CO2
emissions when 12 pieces of goku-wase Satsuma mandarin oranges are packed in a plastic bag andsealed with tape. The plastic bag is made from polyethylene (PE) and weighs an average of 4.1 g. In
the Ajinomoto Group LC-CO2 emissions factor database for food related materials (1990, 1995, and2000 editions; 3 EID compliant (Ajinomoto Co., Inc.), the CO2 emissions in goods made from PE is10.302 g-CO2/g. A tape made of polyethylene terephthalate (PET) weighs 0.1 g on average. In the
Ajinomoto Group LC-CO2 emissions factor database, the CO2 emissions in goods made from PET(excluding fabric goods) is 2.333 g-CO2/g.

16

Table 2. The conditional logit and the random parameter logit regression results in main effects for high and low environmentally conscious groups
Conditional logit
Random parameter logit
Random parameter logit with interactions
Variables

Price
CDE

High

Low

High

Low

Coefficient

Coefficient

Coefficient-0.0974***-0.1190***-0.1054***(0.008)(0.008)(0.010)-0.0774***-0.0404***-0.0897***

0.0782***-0.0446***

0.0810**-0.0610**0.0724**-0.1029***0.0580*(0.008)(0.007)(0.012)(0.029)(0.009)(0.033)(0.030)(0.030)(0.037)(0.034)Standard
deviation-

Coefficient-0.1309***(0.012)High
Standard
deviation-

Coefficient-0.1052***(0.101)-0.0028

CDE × Female(0.030)-0.0125

CDE × Old

(0.033)-0.0234

CDE × High Income(0.021)-0.0028

CDE × University(0.023)Low
Standard
deviation--

Coefficient-0.1303***(0.011)-0.0560***(0.019)0.0362*0.00220.0795**

0.851

0.341

-

-

Log likelihood-547.243-552.238-545.375-550.912-543.750-543.946

0.183

0.208

0.189

0.212

0.191

0.222

2

McFadden’s R
Observations--(0.035)

0.339

-

-

(0.017)0.795

deviation-(0.020)Marginal willingness to pay (JPY)Standard

612
636
612
636
612
636
Notes: Standard errors are in parentheses. ***, **, and * denote that the parameters are different from zero at the 1%, 5%, 10% significance levels,
respectively.

17

Table 3. Average number of times that particular choice reasons are selected and the Friedman test
results of the choice reasons for high and low environmentally conscious groups
High group

Low group

Choice reason

Appearance

Price

CDE

Appearance

Price

CDE

Average number of

5.673

2.885

2.769

5.250

5.096

1.231

selection per reason(3.044)(2.758)(2.813)(3.101)(3.331)(1.660)Appearance

Appearance

Price

Appearance

Appearance

Price-Price-CDE-CDE-Price-CDE-CDE

8.715***

10.946***

0.127

0.251

28.766***23.641***Friedman test
Comparison
Chi-square (2)

N

51

53

Notes: Standard deviations are in parentheses. *** denotes that the parameters are different fromzero at the 1% significance level.

18

Appendix
This supplementary material has four sections. Appendix A provides an example of choice sets.
Appendix B provides three kinds of questions on environment as EC, EK and EB. Appendix C
shows instructions in the experiment. Appendix D provides variables and socioeconomic
characteristics.
Appendix A: An example of choice sets
Satsuma mandarin

Satsuma mandarin

Satsuma mandarinorange Aorange B

orange C□□□

Price (JPY)
Carbon dioxide emissions (grams)
I would choose…
The most important reason affecting my
choice□Price□Carbon dioxide emissions□Others[the reason:□Appearance]

19Appendix B: questionnaire on environment
1. 10 ecologically conscious consumer behavior questions in environmental consciousness (EC)No.

Syntax (cronbach’s alpha = 0.839)

E1
E2
E3
E4

Total

High

Low

I have purchased a household appliance because it

3.436

3.920

2.962

uses less electricity than other brands.

(1.085)(0.882)(1.056)

I have purchased light bulbs that are more expensive

2.767

3.432

2.115

but that save energy.

(1.225)(1.071)(0.994)

I will not buy products that have excessive packaging.

2.951

3.490

2.423

(1.152)(0.916)(1.116)

3.602

4.020

3.192

(0.949)(0.671)(1.001)

2.932

3.451

2.423

(0.927)(0.848)(0.689)

1.980

2.528

1.442

(0.924)(0.893)(0.569)Whenever possible, I buy products packaged in

3.078

3.588

2.577

reusable containers.

(0.952)(0.845)(0.768)

3.544

4.059

3.038

(1.069)(0.850)(1.019)I will not buy a product if the company that sells it is

3.165

3.822

2.519

ecologically irresponsible.

(1.081)(0.858)(0.866)

I do not buy household products that harm the

2.961

3.647

2.288

If I understand the potential damage to theenvironment that some products can cause, I do notpurchase these products.

E5
E6

I have switched products for ecological reasons.
I have convinced members of my family or friends not
to buy some products that are harmful to theenvironment.

E7
E8

When I have a choice between two equal products, I
always purchase the one that is less harmful to otherpeople and the environment.

E9
E10

Average ECCB scale aenvironment.
(1.157)(0.925)(0.948)Notes: Standard deviations are in parentheses.
aScoring scale: always true = 5, mostly true = 4, sometimes true = 3, rarely true = 2, and never true= 1. Higher numbers mean a higher probability of engaging in the particular behavior.

20

2. The 35 eco-labels under the Environmental Knowledge (EK) category:
How many Eco-labels do you know? (Multiple choices permitted)

3. Seven questions of daily life under the Environmental Behavior (EB) category:
To what extent do you act in an environmentally friendly manner? (Multiple choices permitted)
1. I have not used any shopping bags for purchasing anything.
2. I often use public transportation or a bicycle, but not a car.
3. I do not leave the tap running and often turn off a light when not in use.
4. I adjust the room temperature in accordance with health.
5. I always use the stairs and not elevators and escalators.
6. I separate the garbage.
7. Others

Mean
0.660
0.505
0.893
0.786
0.252
0.864
0.136

Std. Dev.
0.474
0.500
0.309
0.410
0.434
0.343
0.343

21

Appendix C: Instruction in the experiment (original text in Japanese)
You are participating in an experiment that is designed to study decision making. In thisexperiment, you will be asked to buy one of three types of Satsuma mandarin oranges, which we will
provide. Please read and follow the instructions carefully. In addition, you cannot communicate withothers during the experiment or take any remaining Satsuma mandarin oranges with you after theexperiment is completed without instructions regarding the same.
Overview
This experiment consists of 12 rounds. In each round, you must choose one of three types ofSatsuma mandarin oranges, which we will provide, and pay for it with the money given to you.
This particular type of Satsuma mandarin orange is goku-wase. It is cultivated in gardens inJapan and you must have seen it in stores. The experimenters have bought them at Japan Agriculture
and some other food stores. At the end of the experiment, the proof of purchase will be shown by theexperimenters.
You will receive your earnings in cash, based on the formula below:
Earnings = 12 * {initial income in each round (120 JPY) – the price of the Satsuma mandarinoranges chosen in each round}+ show-up fees (500 JPY)
Moreover, you can take home the 12 pieces of Satsuma mandarin orange which you choose during
the experiment.
Rules
At the beginning of round 1, you will receive a hypothetical sum of 120 JPY to buy a Satsuma
mandarin orange. You will not actually receive that amount in cash in each round. Please imagine
that you have 120 JPY in each round when you make your choice.
Next, you will receive a box containing three types of Satsuma mandarin oranges and a record
sheet. Verify your seat number and the round number that appear on it.
We will now consider an example of a “record sheet.” This is a record sheet for seat number 1
in round 1. Further, we will explain how to read and fill in the record sheet. The top line, whichstates “record sheet” and “round 1,” indicates the round number and the first seat, which is locatedon the left hand side of the room.
The second line indicates three alternatives —Satsuma mandarin orange A, Satsuma mandarinorange B, and Satsuma mandarin orange C.
The third line indicates the price levels of the Satsuma mandarin oranges in JPY per 100 g. The
price of Satsuma mandarin oranges in each round of the experiment is less than the money you
receive to buy it (i.e., 120 JPY).

22

The fourth line indicates the CO2 emission levels of the three Satsuma mandarin oranges ingrams per 100 grams of Satsuma mandarin orange. These figures indicate the CO2 emission levels
that are produced during the following processes: production, fruit sorting and box packing,transportation and packaging. The CO2 emissions contribute to global warming. The amount of theCO2 emissions is based on data obtained from the Ministry of Land, Infrastructure, and Transport,
The National Institute for Agro-Environmental Science and the Ajinomoto Group in Japan.
The Satsuma mandarin oranges that you are going to choose are of the goku-wase variety,which grow in gardens. The distance between the place of harvest and the store selling the oranges
affects the amount of CO2 that is emitted. For example, the closer the proximity of the selling
location is to the place of harvest, the lower the amount of CO2 emissions is and vice versa.
The fifth line provides space for you to indicate your decision. Please tick in the square that
corresponds to the Satsuma mandarin orange of your choice. So, if you choose Satsuma mandarinorange A, please indicate the same in the corresponding square.
The last line provides the column for you to indicate the reason for your choice. The reasonsfor the choice consist of four factors: price, the CO2 emissions, the appearance of the Satsuma
mandarin orange, and others. Please tick inside the square that corresponds to the reason why you
have selected the particular Satsuma mandarin orange. For example, if you choose price as thereason, you should tick the square in the price column. Finally, close the box and wait for theexperimenter to collect it.
The experimenter will collect all of the boxes in the room. This completes round one. The rules
in round 2 are exactly the same as those in round 1. Initially, you receive 120 JPY, and then, you
receive a box containing three types of Satsuma mandarin oranges and a record sheet. You purchaseone of the three types of Satsuma mandarin oranges. After the completion of round 2, round 3 begins.
This experiment is repeated a total of twelve times following the same rules. The completion ofround 12 signals the end of the experiment.
Earnings
Earnings are calculated as the amount equal to the sum of the participation fee and total of theremaining amounts in twelve rounds. The participation fee is 500 JPY. Since this amount is a reward
for your participation, it is not affected by your choices in each round.
Next, we explain the remaining amounts in the six rounds. At the beginning of each round, you
receive 120 JPY to buy one Satsuma mandarin orange. The remaining amount in each round is equal
to the difference between 120 JPY and the price of the Satsuma mandarin orange you choose. This
amount constitutes your earnings in each round. Since this experiment consists of six rounds, you
receive the sum of the remaining amount for six rounds. The formula for your earnings in theexperiment is provided below.

23

Earnings = 500 JPY (show-up fee)+ {(120 JPY – the price of the Satsuma mandarin orange that you buy in round 1)+ (120 JPY – the price of the Satsuma mandarin orange that you buy in round 2)+...+ (120 JPY – the price of the Satsuma mandarin orange that you buy in round 12)}
You need not be conscious of others because we never offer your earnings to others. Thisconcludes the explanation of the experiment. Please understand the rules of the experiment andselect the Satsuma mandarin orange that you wish to purchase.
Are there any questions before we begin?

24

Appendix D: Socioeconomic characteristics
Variable nameDefinition
Attributes
Price
Price of Satsuma mandarin oranges:25, 35, and 45 JPY perorangeCDE
The amount of carbon dioxide emissions: 20, 30, and 40 gramper orange
Independent variable
CDE × Female
An interaction term of CO2 with a dummy variable that is equal
to 1 if the respondent is female.
An interaction term of CO2 with a dummy variable that is equal
CDE × Old
to 1 if the respondent’s age is over 30 years.
CDE × HighAn interaction term of CO2 with a dummy variable that is equal
Incometo 1 if the respondent’s income is over 5,500,000 JPY
An interaction term of CO2 with a dummy variable that is equal
CDE × University
to 1 if the respondent holds a university or a higher degree
Socioeconomic characteristics
FemaleDummy variable = 1 if the respondent is female

Means (Std)
35
30
0.654
(0.476)
4.125(1.849)Categorical variable (1−6): 1 = below 20, 2 = 20−24, 3 =25−29, 4 = 30−34, 5 = 35−39, 6 = over 40.
Income (JPY)a
Categorical variable (1−5): 1 = below 2,500,000, 2 =
3.851
2,500,000−3,999,999, 3=4,000,000−5,499,999, 4 =(2.060)5,500,000−6,999,999, 5 = above 7,000,000.
Education
2.931
Categorical variable (1−4): 1 = high school; 2 = college; 3 =(0.704)
university;4 = graduate school of university
Notes: a implies that the experiment indicates annual disposable income other than room rental
expenses (JPY).
Age25