UNDERSTANDING CONSUMER INTENTIONS TO ... - ANZMAC

UNDERSTANDING CONSUMER INTENTIONS TO CARPOOL: A TEST OF
ALTERNATIVE MODELS
Lucie Ozanne and Diane Mollenkopf
Lincoln University, New Zealand
This research was made possible by a grant from the Energy Efficiency and Conservation
Authority (ECCA).
Abstract
This study compares two models of consumer intentions to participate in carpooling behaviour; a
Theory of Reasoned Action based model and a model that is based on the Theory of Planned
Behaviour. The two models were compared using data from a sample of 323 respondents who
each completed a web-based survey. Overall, the results suggest that the model based on the
Theory of Planned Behaviour provides a better fit of the data and provides significant insight
into the factors that influence consumer carpooling intentions.
Introduction
The concept of carpooling has been popular since at least the 1940s, when oil and rubber
shortages required consumers to use their vehicles sparingly. Renewed interest in carpooling
was again evident in the 1970s during a major oil crisis (Ferguson 1997). Recent research
suggests that New Zealand commuters are sensitive to carpooling issues and typically support
the concept of carpooling and other rideshare activities that provide alternatives to the 'one
person per car' commute (Mollenkopf and Ozanne 1999). Yet, despite these positive attitudes,
participation in carpooling activities varies widely, and little is known about what motivates or
facilitates commuters to participate in carpooling activities. The academic literature has often
been quick to extol the benefits of ridesharing, but it is only recently that academicians have
begun to investigate those factors that underlie carpooling behaviour.
Prior Carpool Behaviour Research
The rideshare literature can be categorised into groups of factors that affect the propensity of a
commuter to participate in carpooling behaviour: socio-economic characteristics such as age,
gender, income; trip characteristics such as distance traveled, travel time and financial cost of
travel; attitudes toward ridesharing such as convenience, reliability and comfort; subjective factors
such as comfort with interpersonal situations and constraints to independence; or previous
acquaintance with carpool members (Oppenheim 1979; Levin and Gray 1979; Bonsall et al 1984).
Some of the literature focuses on personal versus societal benefits (Bonsall et al 1984). For
instance, personal reasons for carpooling relate to an individual's gains in time or money whereas
societal reasons relate to the desire to help others (Bonsall et al 1984) or to positively influence
the environment (Levin and Gray 1979). Other research focuses on the compatibility of

carpooling with a commuter's life and work, particularly in the commuter/employer relationship.
Company size, assistance in finding carpool partners, worktime flexibility and work schedules
have all been associated with a commuter's propensity to carpool (Cervero and Griesenbeck
1988; Ferguson 1990).
The rideshare literature has been rich and varied in its approach to understanding commuting
behaviour; only a few of the major publications have been discussed here. A major gap in the
carpool literature, however, has been the lack of any systematic approach or underpinning theory
to the research. The wider environmental literature is beginning to develop a theoretical
framework, particularly based on the Theory of Reasoned Action (Fishbein and Ajzen 1975) and
the Theory of Planned Behaviour (Ajzen 1985, 1991). These theoretical approaches are applied
to carpooling in this study in order to better understand the motivations and barriers to
carpooling behaviour.
Applying Marketing Theory to Carpool Behaviour
The Theory of Reasoned Action (TRA) is a theory of attitude-behaviour relationships which
links attitudes, subjective norms, behavioural intentions and behaviour in a fixed causal sequence
(Sparks and Shepperd 1992). Behaviour is asserted to result from behavioural intention, which
in turn is asserted to arise out of a combination of people's attitudes towards performing the
behaviour of interest and their perceptions of the social expectations (norms) put upon them to
perform that behaviour. Attitudes are suggested to arise from a combination of people's beliefs
about behavioural outcomes and their evaluations of those outcomes. Subjective norms are
similarly proposed as arising from a combination of people's perceptions that important others
think they should, or should not, perform the behaviour of interest and their motivation to
comply with the wishes of others (See Figure 1).
Behavioural Beliefs &
Outcome Evaluations
Attitude
Behavioural
Intention
Behaviour
Normative Beliefs &
Motivation to Comply
Subjective
Norms
Figure 1: Model of the Theory of Reasoned Action
The TRA is an appropriate model when behaviour is under an individual's volitional control (i.e.,
if the individual can decide at will to perform or not perform the behaviour). However, the
theory fails to take account of factors that facilitate or inhibit performance of behaviours over
which people have only partial control. The Theory of Planned Behaviour (TPB) extends the
TRA by adding perceived behavioural control as a determinant of behaviour and behavioural
intention, by incorporating a construct that deals with people's perception of control over the
behaviour. That is, their beliefs that they can perform the behaviour if they so desire, that they

have the required time, skills, resources and cooperation of others are expected to be positively
associated with behavioural intentions, and actual behaviour (See Figure 2).
The Present Study
The work by Taylor and Todd (1995, 1997) on composting and garbage reduction behaviour
serves as a foundation for the hypothesised models explaining carpooling behaviour. However,
we have adapted their models as a consequence of a pilot study to elicit salient beliefs related to
carpooling. In our two models, attitude is hypothesised to be positively related to behavioural
intentions. Similar to Taylor and Todd (1997) we hypothesise that both personal and societal
advantages will be positively associated with attitude. However, compatibility beliefs are
believed to be related to attitude rather than perceived behavioural control. This change is also
suggested by the literature on innovation adoption, which suggests that the key determinants of
adoption are relative advantage, compatibility and complexity (Rogers 1983).
Behavioural Beliefs &
Outcome Evaluations
Attitude
Normative Beliefs &
Motivation to Comply
Subjective
Norms
Behavioural
Intention
Behaviour
Control Beliefs &
Perceived Facilitation
Perceived
Behavioural
Control
Figure 2. Model of the Theory of Planned Behaviour
Both internal and external normative beliefs about carpooling are hypothesised to be positively
related to subjective norms. In the TPB model, perceived behavioural control is hypothesised to
be composed of beliefs about resource facilitating conditions and beliefs about the ability to
carry out the behaviour, or self-efficacy. Although not part of the TRA or TPB, previous research
has suggested the importance of past behaviour in predicting current or future behaviour
(Norman and Conner 1996; Van Ryn et al. 1996; Reinecke et al. 1996). Therefore, past
experience with carpooling is hypothesised to have a direct relationship on future carpooling
intentions, as well as an indirect relationship on behavioural intentions via attitudes. For this
study an actual measure of carpooling behaviour was not feasible. Thus, this research focuses
upon the relationship between behavioural intentions and the independent variables. See Figures
3 and 4 for the TRA and TPB based models.

The study was conducted in a field setting using survey methodology. A web-based
questionnaire was used to collect data. Development of the scales to measure each of the
constructs in the model proceeded through a series of steps, based on the procedures suggested
by Ajzen and Fishbein (1980) and Ajzen (1985, 1991). The questionnaire was then subjected to
two rounds of pretesting on the web prior to sending out the final instrument.
Results
A total of 956 e-mail letters were sent to staff at a New Zealand university and local research
organisations. From this sample pool, 323 useable responses were received, for an effective
response rate of 34%. Before commencing analysis of the theoretical models, all variables were
examined for reliability, validity and normality, and were deemed adequate for further analysis.
Each of the two models presented above was then subjected to path analysis testing, using
AMOS 3.6 software for structural equation modeling. A path analysis approach was used
because all variables were manifest rather than latent. Introducing latent variables in addition to
the manifest variables would have required a larger sample size.
The data did not prove to be a good fit for the proposed TRA model. The best model, achieved
had a Chi square of 160.12, 11df. Although 41% of the variance in carpool behavioural intention
was explained in the model, the root mean square error of .21, p=.00 indicated the poor fit of the
model to the data.
Carpooling intentions were better explained when the data were tested using the TPB model.
However, the model did not fit exactly as hypothesised. The best fitting model, presented in Figure
3, achieved a Chi square of 14.95, 5df, with a rmsea of .08, p=.13.
SRA
PRA
COMPAT
EXPER
INT_NORM
.18
.23
.30
.22
0, 1
err1
.78
.40
ATTITUDE
.13
.20
SUBNORM
.37
0, 1
Err4
.70
.50
INTENT
Hypothesised
relationship (not
significant)
Hypothesised
relationship
(significant at p ≤ .05)
Significant
relationship (p ≤ .05),
not hypothesised
Significant covariance
relationship (p ≤ .05)
EXT_NORM
FAC_RES
SELF_EFF
.40
.19
Err2
0, 1
PB_CONT
.87 0, 1
Err3
.25
.29
Chi square = 14.95
df = 5 p = .01
cmindf = 2.99
rmsea = .08
p of close fit = .13
Figure 3. Carpooling Behaviour as Explained by the Theory of Planned Behaviour

Discussion and Conclusion
The intent of this study was to compare two models of consumer intentions to participate in
carpooling behaviour, based on the TRA and the TPB. Both models are based on a theoretical
foundation but also incorporate many of the factors that have been found to be related to many
environmental behaviours.
Although the TRA model has been useful in a number of other settings (Sheppard et al 1988), this
model does not do an adequate job of explaining carpooling behaviour. This finding supports the
results of other studies that have used the TRA to understand environmental behaviours (Bagozzi
and Dabholkar 1994; Goldenhar and Connell 1993; Taylor and Todd 1997). This suggests that
carpooling behaviour is not purely volitional and other factors, such as perceived behavioural
control, need to be incorporated to augment the TRA model.
The TPB does provide a stronger basis for exploring the relationships and predicting carpooling
behaviour. First, Attitude is the key determinant of Behavioural Intentions, suggested by the strong
statistical link between ATTITUDE and INTENT. Thus, the more convenient, flexible and pleasant
a respondent finds carpooling, the more likely s/he is to engage in carpooling behaviour. In turn,
Attitude towards carpooling is positively influenced by Personal Relative Advantages, as predicted.
That is, the more a respondent felt that s/he could save money, reduce wear and tear on the car, find
a carpark more easily, or interact with others, the more favourable his/her attitude towards
carpooling. Compatibility is also positively related to Attitude, as expected. This means that to the
extent that carpooling does not compromise a respondent’s flexibility, independence, work
hours/schedule, or other commitments, the more favourable his/her attitude towards carpooling.
Additionally, Compatibility is also directly related to Behavioural Intention, as indicated by the
significant link between COMPAT and INTENT. This had not been hypothesised from theory and
is an important finding in understanding carpool behaviour because of the direct effect that
incompatibility may have on one’s carpool intentions.
Attitude is also positively influenced by having previous carpool experience, as predicted. This
relationship had not been suggested in the TPB, but has been suggested in previous research.
Thus, the addition of this variable to the theoretical model has helped provide additional
explanatory power to the model.
Surprisingly, Facilitating Resources were also found to be positively related to Attitude, as this
had not been foreseen in the theoretical model based on the TPB. However, it does make
intuitive sense that to the extent someone has the resources to engage in carpooling (eg, having
access to others who want to carpool, an ‘arrangeable’ work schedule, and time to plan for
carpooling arrangements), the more positive one would feel about carpooling. Thus, the
relationship between Facilitating Resources and Attitude is an important finding.
Second, Subjective Norm (as measured directly, or through internal and external influences) is
not related to carpooling intentions . This finding is contrary to the Theory of Planned
Behaviour, but is an important finding in carpool research in New Zealand.
Third, Perceived Behavioural Control is directly related to Behavioural Intentions, as predicted.
This means that non-motivational factors such as the amount of control one perceives over

commuting options, one’s perceived ability to undertake carpooling, or the perceived ease of
carpooling, are positively related to carpooling intentions. This is supported by the positive
relationship between Perceived Behavioural Control and Facilitating Resources, and suggests the
importance of resources to one’s sense of control over a situation.
Fourth, previous experience was also found to be directly related to Perceived Behavioural
Control. While this relationship had not been predicted, it makes sense that having had previous
experience would increase one’s sense of control in carpooling situations. Experience was also
found to be directly related to Behavioural Intention, as predicted. The importance of
Experience in influencing Attitude, Perceived Behavioural Control and Behavioural Intention are
all important findings, and have implications for promotion and policy actions.
Although the intent of this study was to compare two models of consumer intentions to
participate in carpooling, the findings also provide insight for increasing carpooling behaviour.
In the carpooling setting, the intention to carpool is determined by one's attitudes toward
carpooling, perceived control over carpooling behaviour, and previous experience. Thus,
policymakers should concentrate on tools to influence attitudes and perceived behavioural
control. Further policy insights can be found in Mollenkopf and Ozanne (1999).
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