Abstract
Introduction
With the development of information technology, its application in the health industry has become a hot research area in both China and some other countries, 1 gradually forming a new research field called e-health. 2 Currently, the popularity of mobile devices has greatly promoted the development of e-health. As a result, mobile health services have come into being. 3,4 M-health means using mobile communications and network technologies in healthcare systems. 5 The usage of m-health has gained additional dimensions in recent years.
With potential benefits including more efficient healthcare, available remote medical monitoring and consultation, reduced cost, etc., there is a scant body of literature on the adoption of m-health. 6 Istepanian and Lacal 4 did a brief overview of the development trend of m-health services; they believed that the biggest obstacle to the development of m-health was the connectivity and compatibility between mobile devices. Jones et al. 7 pointed out that m-health technology merges personal wireless communications equipment, medical equipment, and network equipment together so as to provide patients with daily health services. Through simulation, Liang et al. 8 verified that the emergency call mode of m-health could reduce the responding time in emergency situations.
Research studies in behavioral aspects mainly consider m-health as a technology, studying people's adoption intention using the theoretic lens of the technology acceptance model (TAM), the motivational model, and others. Wilson and Lankton 9 applied the TAM model to the health information technology (IT) area; they found that perceived ease of use and perceived usefulness affect the patients' intention to adopt e-health. López-Nicolás et al. 10 used the TAM model as a basic model to study m-health usage intention and verified that perceived ease of use and perceived usefulness have a positive influence on patients' m-health adoption. Mohamed et al. 11 applied the TAM model to explore m-health users' attitude and also verified the model's basic conclusion. Cocosila 12 used the motivational model to study how prior attitude influences m-health adoption behavior and found that intrinsic motivation and extrinsic motivation have positive effects on m-health adoption. López-Navarro et al. 13 studied the adoption of m-health from the perspective of health risk perception and trust in public.
The theoretical framework for this study is based on the theory of reasoned action (TRA) model. From the perspective of social psychology, the TRA model takes attitude and subjective norms as the key factors of behavior intention, 14 which is one of the most basic and influential IT acceptance models. 15 Ajzen 16 pointed out that in some specific areas, the explanatory ability of the model could be enhanced by modifying the model's theory mechanism. The model enhances our comprehension of how attitude and subjective norms (SNs) affect technology adoption, but it ignores the nonlinear relationship between two key constructs. 17
Although we take the user's perceived ease of use, perceived usefulness, age, motivation, and other factors into consideration while studying m-health adoption, there are also some consumer attributes not incorporated. 18 Although numerous studies in various settings have extensively involved the impact of gender, such as on buying behaviors 19 and on blog switching behavior, 20 the role of gender in m-health adoption has rarely been studied.
Thus, this study aims to fill the research gap by applying a modified TRA model to m-health research. The purpose of this research is to determine whether by incorporating the nonlinearities of independent variables and the mediator gender into the TRA model we can predict users' m-health adoption intention and to study the gender differences in the intention, especially the gender differences in the nonlinearities. The remainder of the article is organized as follows: in the next section, we elaborate on the theoretical foundations and hypotheses of this research, and then we provide an overview of the proposed methodology, followed by a discussion of the results and a conclusion to our research work.
Materials and Methods
M-Health
As a type of e-health services, m-health mainly provides health services through mobile devices. The major functions of m-health consist of health consulting, hospital registering, and location-based services. 21 M-health has more advantages over e-health in portability, mobility, and ubiquity, 22 so it features personalization, interactivity, and generalization.
In terms of the functions, m-health services can be classified into five types:
1. Health information retrieval. Through m-health services, users can query health information, emergency measures of all kinds of common diseases, and visiting time. 23
2. Remote reservation. Users can register through intelligent mobile devices and visit doctors according to the appointed time. 24
3. Remote diagnosis. Users can record physical indicators data using digital detection equipment and upload the data to service platforms through mobile devices, achieving real-time detection, diagnosis, and monitoring of user health status. 25
4. Electronic medical records access. Users can log-on to m-health service platforms, refer to their electronic medical records, and browse the results or reports as well as doctors' advice information. 26
5. Health consultation. M-health service platforms also periodically send health guidance, disease prevention and controls, appointment notices, doctors' advice statements, and some specific notices or reminding to users. 27
As m-health is a new, emerging phenomenon, empirical studies on these issues are still rare. Mohamed et al. 28 tested whether technology design affected acceptance of m-health informatics. Hung and Jen 29 discovered that the perceived usefulness and perceived ease of use are different for different m-health adopters through the TAM model and that the impact of age factor is also significant at the same time. Akter et al. 30 studied the degree of acceptance of m-health information services and pointed out trustworthiness as a secondary variable has direct and indirect effects on continuous intention, but there is no mediating role. Wu et al. 31 studied acceptance of m-healthcare systems with the TAM model and the diffusion of innovations theory and found that compatibility and self-efficacy affect both perceived usefulness and perceived ease of use, whereas technical support and training have no significant effects. Yang and Wang 32 studied acceptance behavior for asthma care mobile service and added SN and attitude toward use to the TAM model, finding that SN has direct and indirect impact on behavior intention and that the perceived ease of use and attitude toward use can mediate the perceived useful effects on the dependent variable. Thus, in m-health contexts, the TRA model is rarely used.
TRA Model
The TRA model explains or predicts individual specific behaviors in many areas with volitional control and achieved good effects. 14,33 The premise hypothesis of the model is that people's behavior intention influence their behaviors, and, in turn, behavior intentions are influenced by attitude and SN. “The attitudinal component refers to the person's attitude toward performing the behavior under consideration,” 14 whereas the normative component refers to “The person's subjective norm, that is, his perception that most people who are important to him think he should or should not perform the behavior in question.” 14 So the basic framework of the TRA model is that behavior is affected by behavior intention, and behavior intention is affected by the inner factors attitude toward the behavior (ATTB) and SNs.
In addition to internal factors, behavior intention is also affected by external factors such as facilitating conditions (FC).
34
The term FC means resources needed to achieve the behavior such as time, knowledge, and other specialized resources.
35
Much research has introduced FC into the TRA model and tested their impacts on behavior intention.
17,36,37
Thus, the common modified TRA model is formed with attitude, SNs, and FC as independent variables.
17,36,37
Thus, we suggest these hypotheses:
Nonlinearities between ATTB and SN
Although attitude and SNs are two key constructs of the TRA model, 14,16 the nonlinearities between them are often overlooked. The hypothesis based on the theoretical independence between them is likely to underestimate or overestimate the explanatory ability of their interpretation of behavior intention, 38 and their nonlinearities are seldom incorporated in the model on IT contexts. 17 Rabow et al. 39 discovered that ATTB * SN has a strong influence on behavior intention in the study of adult alcohol consumption. Terry et al. 40 verified that ATTB * SN can well predict behaviors. Titah and Barki 17 first introduced ATTB * SN as a fourth variable to the TRA model to explain IT acceptance and found that the explanatory ability of the model was improved.
Current articles have proven an Edgeworth–Pareto substitutability between ATTB and SNs. 17,40,41 The Edgeworth–Pareto substitutability declares that if the combined influence of the two factors is weaker than the sum of two variables' independent influence, there is a negative synergy. 17 So when the influence of a factor increases, the marginal effect of another factor will be reduced. Instead, complementarity means that when the influence of a factor increases, the influence of another factor will be increased. The relationship above can be illustrated by the following formulas:
Assume that X
1 and X
2 are impact factors of Y, and considering their nonlinear relationship, the function can be written as
When β 3>0, X 1 and X 2 are complements; when β 3<0, X 1 and X 2 are substitutes; and when β 3=0, X 1 and X 2 are independent.
M-health is accepted by users voluntarily. Users can decide on the application degree and extent according to their requirements. But when one is influenced by strong SNs (relatives, influential people) and then has m-health adoption intention, changes in his or her attitude will only slightly influence his or her adoption intention. In turn, when one has a very positive attitude toward m-health, thinking that m-health is particularly useful, changes in SNs will only slightly influence the adoption intention.
42
So the Edgeworth–Pareto substitutability between attitude and SNs in m-health adoption intention seems plausible. Thus, we suggest:
Gender Differences
The influences of personal characteristics on behavior intention has attracted considerable research attention. 19,33 In IT acceptance contexts, Gefen and Straub 43 added the factor of gender into the TAM model as a part of social and cultural factors to IT context, drawing the conclusion that the influences of perceived ease of use and perceived usefulness in e-mail technology diffusion differ by gender. Venkatesh et al. 2 put gender and other factors (age, experience, etc.) as moderator variables into the unified theory of acceptance and use of technology model. Okazaki and Mendez 44 took gender as a moderator in mobile commerce acceptance and found that there is a gender difference. In TRA model applications, Al-maghrabi and Dennis 45 used the TRA model to study the factors of continuance online shopping and found the gender differences cannot be ignored. Ryu and Han 33 introduced gender into the TRA model to study tourists' behavioral intention and found that gender had a significant influence on the relationship between attitude and behavior intention but no significant influence on the relationship between SNs and behavioral intention.
According to social role theory, women and men play different roles and behave differently in society because they are socialized differently. 46 Women in general are relatively passive and do not like to adventure. Instead, men are more active and adventurous, so men are more positive about exploring new things. 47 “Many researchers have proposed that women are characterized as more communal while men as more agentic.” 20 In particular, women are likely to be more anxious about mobile technology. 48 On the other hand, men are expected to be more task-oriented than women. If they or their friends think something is useful and important, they may have a higher level of usage intention. 49 Lin et al. 50 found that the positive influence of perceived usefulness on Facebook continuance intention will be stronger for men than for women. Venkatesh et al. 51 suggested that men tend to rely less on FC when considering use of a new technology, whereas women tend to place greater emphasis on external supporting factors.
So the gender factor may affect m-health services adoption intention. We incorporated gender as a moderator variable into the model, exploring the gender differences in the relationship between dependent and independent variables. Thus, we suggest:
In summary, this article was designed (a) to examine the construct validity of a modified TRA model in explaining people's m-health adoption intention, (b) to study the effects of FC, attitude, and SN on m-health adoption intention, (c) to test the effect of the nonlinearities relationship between ATTB and SN on m-health adoption intention, (d) to discover the effects of gender as a moderator variable in a modified TRA model, and (e) to discover the gender differences of the nonlinearities relationship between ATTB and SN. Figure 1 presents the proposed model of our research.

Proposed model. The dotted lines signify the moderating effect. AI, adoption intention; ATTB, attitude toward the behavior; FC, facilitating conditions; SN, subjective norm.
Results
Data Collection and Measures
To test the study hypothesis, we used a questionnaire to collect data in a field survey of customers of a large company providing m-health services in Harbin, China. Construct measures were adapted from previous studies with all items assessed on 5-point Likert-type scales. To ensure our data were robust, we distributed our questionnaires in different industries and covered people of different ages. We sent out 510 questionnaires, from which 481 valid questionnaires were collected after removing the invalid returns. Table 1 shows the demographic information of our respondents.
Respondent Demographics
As shown in Table 2, a preliminary assessment of the survey instrument was conducted by partial least squares (PLS). It shows that the composite reliabilities are greater than 0.85 and that the average variances extracted are greater than 0.65, highly above the suggested cutoff values of 0.70 and 0.50, respectively. 52,53 Factor loadings are found to be significant and higher than 0.70. All these suggest good construct reliability.
Measures for Constructs
Data are for total population/males/females.
AI, adoption intention; ATTB, attitude toward the behavior; AVE, average variances extracted; CR, composite reliability; FC, facilitating conditions; m-health, mobile health; SN, subjective norm.
The discriminant validity can be assessed by comparing the square root of average variances extracted and the correlations. 55 As shown in Table 3, from the item-level correlation matrix we can observe that all the correlations are lower than the root of average variances extracted. Therefore, the discriminant validity is acceptable. Thus, our measurement model has been tested as reliable.
Discriminant Validity for Constructs
Data are for total population/males/females.
AI, adoption intention; ATTB, attitude toward the behavior; FC, facilitating conditions; SN, subjective norm.
Structural Model
The model analysis is conducted in two stages. In the first stage, to test our model and the role of the nonlinearities between ATTB and SN, we built model M1 without the nonlinearities and model M2 with the nonlinearities. We used PLS to test our models with all of the data. The results are shown in Table 4.
Partial Least Squares Results in Stage 1
AI, adoption intention; ATTB, attitude toward the behavior; FC, facilitating conditions; SN, subjective norm.
Second, to discover the role of gender moderator, we divided our data into two parts according to gender and tested our modified model separately. To perform the subgroup analysis, we used the formula suggested by Ahuja and Thatcher 56 to calculate the discrepancy of the designated paths by the standard error and the corresponding path coefficient. The results are shown in Table 5.
Partial Least Squares Results in Stage 2
AI, adoption intention; ATTB, attitude toward the behavior; FC, facilitating conditions; SN, subjective norm.
Discussion
Our research aims to inspect one modified TRA model and the mediating role of gender in explaining people's m-health adoption intention. Furthermore, we examine the Edgeworth–Pareto substitutability between attitude and SNs and its gender differences.
Findings
First, the effects of FC, attitude, and SNs on behavioral intention are tested. The regression path from FC to adoption intention is significant, thus supporting Hypothesis 1. FC have a positive influence on m-health adoption intention. It means that if someone possesses or he or she thinks he or she possesses the right thing necessary for m-health usage, he or she would have a high stage of adoption intention. The regression path from attitude to adoption intention is significant, thus supporting Hypothesis 2. It means that if one has a positive attitude toward m-health, he or she would expect to use m-health services. The regression path from SNs to adoption intention is also significant, thereby supporting Hypothesis 3. It demonstrates that one would have a higher probability to adopt m-health services if other people who are important to him or her or can influence him or her to think he or she should. All the factors are significant, and the model explains a certain proportion (33.6%) of the variance in adoption intention, indicating that the TRA model can be used in m-health contexts.
Second, from the comparison of Model 1 and Model 2 we can come to a conclusion that when incorporating the nonlinearities between ATTB and SN, the nonlinear model explains a significantly greater proportion of the variance than the linear model (33.6% versus 40.7%), indicating that the nonlinear model predicts behavior better. What is more, the effect of the nonlinearities between ATTB and SN is significant and negative (β=–0.376, t=2.098, p<0.01); thus the Edgeworth–Pareto substitutability between attitude and SNs is proved in m-health adoption.
Third, as shown in Table 5, the two groups had a significant difference in m-health adoption intention. From whichever aspect, FC (0.242 versus 0.222, t=5.605, p<0.01), attitude (0.331 versus 0.284, t=5.430, p<0.01), or SNs (0.570 versus 0.212, t=39.44, p<0.01), males always have a higher level of m-health adoption intention compared with females. Thus, our Hypotheses 5–7 are all supported, and we can conclude that men find it easy to adopt m-health. In particular, the estimates for path coefficients from SNs to adoption intention across groups have a significant difference, indicating that men find it easier to adopt m-health when influenced by important or influential people.
Finally, we come to the gender differences on the nonlinearities between ATTB and SN. From Table 5, based on the data from the study population in China, we also find that the path coefficient from the interaction to adoption intention is significant in the male group (β=–0.300, t=8.082, p<0.01) but not significant in the female group (β=–0.115, t=0.569, p>0.1). So for men, when attitude is high, increases in SNs have a decreasing marginal impact on adoption intention. Alternatively, when SNs are high, increases in attitude have a decreasing marginal impact on adoption intention. But, for women the phenomenon is not significant. So men have an Edgeworth–Pareto substitutability between attitude and SNs, whereas women do not. What is more, for men the modified TRA model explains 52.9% of the variability of adoption intention, but for women it is only 25.6%. So other factors may exist affecting women adopting m-health besides social psychological factors. So the modified TRA model fits males better.
Limitations and Future Research
Some limitations still exist in the present study. This article only involves one nonlinearity; the others such as FC*ATTB or FC*SN are not incorporated, which have been studied by Bansal and Taylor 57 but have not been introduced to m-health adoption research. Second, the modified TRA model fits the male gender well, but for the female gender the model fails to explain the variability by more than 30%; in other words, our model does not incorporate the main factors of female. Finally, although we have found that women do not have an Edgeworth–Pareto substitutability between attitude and SNs, we did not find out the inherent reasons. Our future research aims to develop a suitable model to explain the m-health adoption behavior and find out the reason why females and males perform differently according to the nonlinearities between ATTB and SN.
Contributions
In spite of these limitations above, the study makes several theoretical contributions. First, the study introduces a modified TRA model with the nonlinearities between attitude and SNs to explain or predict people's m-health adoption intention for the first time. Second, we use gender as a moderator into the modified TRA model and discover the gender differences of the relationship between social psychological factors and m-health adoption intention. Third, we find that the modified TRA model based on social psychological factors fits men better than women for the reason that they are differently socialized. 46 Finally, for the first time we find the gender differences of the Edgeworth–Pareto substitutability between attitude and SNs in m-health adoption.
On practical grounds, the findings of the present study have value for m-health services providers. The Edgeworth–Pareto substitutability between attitude and SNs means that the high level of one factor can compensate for the other factor in low level. Providers can use this mechanism to gain deeper insights into the interaction of attitude and SNs. To develop male users, they can take advantage of the substitution effect to make informed decisions on how much effort to invest to enhance potential users' positive attitude or strong SNs.
Conclusions
Although m-health services have drawn considerable attention in the research field of the world today, studies on the relationship between social psychological factors and m-health adoption are rarely conducted. The proposed research model reveals the effect of the nonlinearities between attitude and SNs and the role of the moderator gender. Our findings are as follows: (1) when the TRA model includes the nonlinearities, it may enhance the explaining ability of the model; (2) males have a higher-level adopt intention of m-health compared with females; (3) the modified TRA model predicts males' behavior intention better than that of females; and (4) Edgeworth–Pareto substitutability exists between attitude and SNs in explaining m-health adoption intention, but this phenomenon exists only when it comes to males. Our study provides a new understanding on both gender differences in m-health adoption and the TRA model usage.
Footnotes
Acknowledgments
This study was partially funded by the NSFC 71101037, NCET-12-0146, and the Hong Kong Scholars Program. We would like to thank the editors and two anonymous reviewers for their insightful comments and suggestions.
Disclosure Statement
No competing financial interests exist.
