Examining the impact of social influence on purchase behavior of online food delivery in Vietnam: The moderating role of trust and physical obstacles during the COVID-19 Pandemic

This article investigates the impact of social influence on online food delivery (OFD) purchase behavior in Vietnam, specifically examining the moderating role of trust and physical obstacles during the COVID-19 pandemic. A total of 378 respondents participated in the research, and the findings highlight the significance of social networks and interpersonal relationships in the OFD market. Regarding the role of trust as a moderator, the findings highlighting the importance of building trustworthiness and credibility in the OFD industry. The findings suggest that physical obstacles, such as the closure of non-essential stores and social distancing measures, weaken the influence of social factors on consumers' behavior. These changes in individuals' lifestyles have introduced physical barriers to traditional dining experiences, consequently increasing reliance on online food delivery (OFD) services. Overall, this study contributes to the existing literature on consumer behavior and provides insights for industry practitioners and policymakers to develop effective marketing and communication strategies and support mechanisms to facilitate the growth and sustainability of the online food delivery industry in Vietnam.


Introduction
The e-commerce industry has witnessed a remarkable surge in growth in recent years, driven by various factors including advancements in technology, changing consumer behaviors, and the increasing reliance on online platforms for services.While the COVID-19 pandemic had brought significant challenges to the overall food service sector, it has also acted as a catalyst for the rapid expansion of the online food delivery (OFD) services market (Ali et al, 2020).Government policies implemented to curb the spread of the virus, such as restrictions on indoor dining and social gatherings, have compelled restaurants to shift their focus towards delivery and takeout options (Lee & Ham, 2021).This shift, coupled with advancements in technology and the increasing reliance on digital platforms, has fueled the growth of the OFD market.
The surge in popularity of online food delivery (OFD) services has sparked the interest of researchers and practitioners, highlighting the importance of understanding the factors that influence consumers' adoption and usage of these platforms.Previous studies have contributed valuable insights into customers' decision-making processes and behavioral intentions regarding OFD services.Yeo et al. (2017) explored the motivations driving customers' use of OFD services, while Ray et al. (2019) identified key factors influencing the adoption of OFD service.However, the pandemic has significantly altered human behavior patterns, making it essential to consider this contextual factor when examining customers' use of OFD services (Hong et al, 2021).
2 Social influence, which refers to the impact of interpersonal relationships, social norms, and peer recommendations on individual decision-making processes (Bagozzi, 2000), plays a significant role in shaping consumers' attitudes, intentions, and purchase behavior.This means that consumption behavior may be influenced by socialization forces due to the desire to align one's behavior with referent group norms.Previous research has demonstrated the positive influence of social influence on consumers' willingness to adopt and utilize OFD services (Hutabarat et al, 2021;Karulkar et al, 2019;Pokhrel & Shah, 2022).The findings consistently demonstrate the positive impact of social influence on consumers' willingness to adopt and utilize these services.Consumers are more likely to engage in OFDS when they perceive positive recommendations and social norms from their social circles.
In addition, it is important to consider potential moderators that may influence the relationship between social influence and consumption behavior.For instance, trust has been identified as a critical factor that shapes consumers' reliance on social influence and recommendations from reference groups (Rehman et al, 2019).Physical obstacles, such as those imposed during the COVID-19 pandemic (e.g., lockdown measures, limited dining options), can also moderate the impact of social influence on consumption behavior (Hesham et al, 2021).
While existing literature on online food delivery services (OFDS) has examined the various dimensions of theoretical frameworks and their impact on behavioral intentions in the context of online food delivery services (OFDS).However, there is a scarcity of studies that specifically investigate the influence of a single construct on purchase behavior while considering two crucial moderating variables, namely trust and physical obstacles.Moreover, the exploration of the moderating roles of trust and physical obstacles, which are highly relevant in the context of OFDS, has received insufficient attention.Therefore, understanding the interplay between social influence, trust, physical obstacles, and purchase behavior in the context of OFDS is crucial for both researchers and practitioners.By delving deeper into these factors, this study aims to bridge the existing research gap and provide valuable insights into the mechanisms through which trust and physical obstacles influence consumers' decision-making and subsequent purchase behavior.The findings from this research will offer practical implications for businesses operating in the online food delivery sector, enabling them to develop tailored strategies to foster trust, overcome physical obstacles, and ultimately optimize their customers' purchase behavior and promote OFDS adoption and usage in Vietnam.

Conceptual Background, Empirical Review and Hypotheses Development Online Food Delivery Service in Vietnam
In recent years, the online food delivery (OFD) service industry has experienced significant growth in Vietnam, driven by technological advancements and changing consumer behaviors.According to the latest statistics, the market for OFD in Vietnam has been on a continuous upward trend, with substantial revenue potential in the coming years.In 2020, the OFD market in Vietnam reached a market size of nearly 587 million US dollars, with a compound annual growth rate (CAGR) of 96.8% from 2016 to 2020 (Statista, 2022).This remarkable growth can be attributed to several factors.Firstly, the increasing adoption of smartphones and internet penetration in Vietnam has made it easier for consumers to access online platforms and place food delivery orders.As of 2020, the smartphone penetration rate in Vietnam reached 70.2%, and internet penetration stood at 69.4% (Statista, 2022).Secondly, the COVID-19 pandemic has acted as a catalyst for the growth of the OFD market in Vietnam.Government-imposed restrictions on indoor dining and social gatherings during the pandemic prompted consumers to turn to online platforms for food delivery services (Lee & Ham, 2021).These measures created a significant shift in consumer behavior, increasing the reliance on OFD services as a safer and more convenient option.Furthermore, the rising popularity of food delivery platforms and the availability of diverse cuisines and restaurant options have contributed to the growth of the OFD market.According to Statista (2021), the global OFD market is projected to reach a value of 154.34 billion US dollars in 2023, with Vietnam expected to be a key contributor to this growth.Several studies have examined the factors influencing consumers' adoption and usage of OFD services in Vietnam (Kim et al, 2018;Nguyen et al, 2022;Tran & Tran, 2020) investigated the factors influencing customers' intention to use OFD services among Vietnamese consumers.Their findings highlighted convenience, time-saving, and a wide variety of food options as primary drivers of OFD adoption, while concerns about food quality, delivery delays, and additional costs were identified as barriers to usage.
Considering the impact of COVID-19 pandemic on consumer behavior, Nguyen et al. (2021) assessed the impacts of perceived risks on food purchase intention through online channels among Vietnamese consumers during pandemic.They found that product risk, security risk, time risk, and fraud risk associated with online sellers negatively influenced consumers' intentions to purchase food online in Vietnam.Similarly, Le et al. (2022) examine the technological and psychological motives influencing the usage behavior of OFD services during the COVID-19 epidemic in Vietnam.This result revealed that trust and social influence played significant roles in the acceptance of OFD technology, aligning with the predictive power of these factors in the traditional Technology Acceptance Model (TAM) framework.Nhung et al. (2020) examined the impact of the COVID-19 pandemic on users' continuous intention to use food delivery applications in Vietnam, using the Unified Theory of Acceptance and Use of Technology 2 (UTAUT2) model as their theoretical framework.They found that social influence, particularly through social connections like peers, family, or reviewers, influenced consumers' intention to use food delivery applications.

The Role of Social Influence on Purchase Behavior
Social influence, defined as the impact of interpersonal relationships, social norms, and peer recommendations on individual decisionmaking processes, plays a crucial role in shaping consumers' attitudes, intentions, and purchase behavior (Bagozzi, 2000).The role of social influence in shaping consumers' attitudes and behaviors, particularly in the context of online food delivery (OFD) services, has been widely acknowledged.Understanding the role of social influence in consumption behavior is of significant importance in the context of online food delivery (OFD) services, where consumers rely on recommendations and social norms to make decisions.Studies have consistently demonstrated the positive impact of social influence on consumers' willingness to adopt and utilize these services.Lee et al. (2019) conducted research in South Korea, revealing that positive peer recommendations significantly influenced consumers' intentions to use OFD platforms.Similarly, Bao and Zhu (2022) investigated the influence of social norms on the adoption of OFD services in China and found that individuals were more likely to engage in OFD when they perceived positive social norms from their reference groups.Belanche et al. (2020) delved into the technological and sociological factors motivating customers to use and recommend food delivery services.Their findings emphasize the significance of subjective norms as a form of social influence, shaping individuals' decisions regarding food delivery apps.Gunden et al. (2020) explored the impact of social influence on consumers' spontaneous behavioral choices when using online food delivery services.Grounded in persuasion theory, their study shaded light on the persuasive effects of social influence in the context of online food delivery.Thus, the following statement presents hypothesis 1 proposed by this study.H1: Social influence positively impacts purchase behavior.

Moderating Effect of Trust
Numerous studies have consistently emphasized the crucial role of trust in facilitating customers' utilization of online services (Eneizan et al, 2021;Hu et al, 2019;Qalati et al, 2021;Rehman et al, 2019).Qalati et al. (2021) delved into the association between antecedents of trust in online shopping and purchase intention, shedding light on the moderating effect of trust in the relationship between perceived risk and purchase intention.The study revealed that trust plays a crucial role in influencing consumers' purchase intention, and this relationship is contingent upon the level of perceived risk.Interestingly, under conditions of high perceived risk, the relationship between trust and purchase intention becomes stronger, indicating that trust serves as a significant mitigating factor when consumers face uncertainties in their online shopping experiences.Rehman et al. (2019) explored the relationship between the theory of planned behavior, technology acceptance model elements, and consumer purchase intention in the context of online shopping, while considering the moderating roles of trust and commitment.The findings of this study underscored the positive and substantial influence of trust on consumers' online shopping behavior.In essence, trust emerged as a moderator, strengthening the relationship between purchase intention and online shopping behavior.This implies that the more trust consumers have in online retailers, the more likely they are to engage in online shopping behavior.
Building upon the insights from these studies, Zhang et al. ( 2022) developed a comprehensive model to investigate the determinants of customers' trust in live-streaming commerce and its impact on customers' continuance intention.Acknowledging the growing significance of social interactivity and technology features in the emerging field of e-commerce, the study specifically focused on their effects on trust, subsequently influencing users' continuance intention.The empirical findings demonstrated that trust can be enhanced through live interactivity and technical enablers, thereby influencing customers' intentions to continue using live-streaming commerce platforms.Additionally, the study revealed that consumers who perceive higher levels of trust are more inclined to be influenced by social recommendations and actively participate in online group-buying activities.Thus, the following statement presents hypothesis 2 proposed by this study.H2: Trust strengthens the relationship of social influences and consumption behavior.

Moderating Effect of Physical Obstacles (COVID-19 pandemic)
The COVID-19 pandemic has introduced unprecedented physical obstacles that individuals face when engaging in various behaviors.These obstacles have been primarily driven by social distancing measures and the closure of non-essential stores, significantly impacting people's lifestyles and psychological characteristics (Shepherd et al, 2021).The effects of lockdowns have been extensively studied, highlighting the profound influence of physical barriers on individuals' lives.
In the context of the retail industry, the closure of brick-and-mortar stores has led to immediate changes in consumer behavior.Nguyen et al. (2020) identified this closure as a key driver for the rapid adoption of the Bricks and Clicks model in Vietnam.This shift towards online channels reflects how physical obstacles can prompt consumers to seek alternative modes of consumption.
Considering the situational influences caused by the COVID-19 pandemic, Ali et al. (2020) introduced physical obstacles as a moderating variable in the relationship between behavioral intention and actual purchase behavior.By acknowledging the unique circumstances imposed by the pandemic, this study aimed to examine how physical barriers affected the association between consumers' intentions and their subsequent purchase behavior.Additionally, Zarei et al. (2019) proposed that situational factors in shopping, including physical obstacles, store atmosphere, and antecedent states, play significant roles.In line with this perspective, the present study incorporates these three elements as the situational determinants influenced by the COVID-19 context.The inclusion of 'social distancing' as an additional situational factor influencing online shopping intent during the COVID-19 pandemic further enriches the understanding of the impact of physical obstacles on consumers' behavior.Thus, the following statement presents hypothesis 3 proposed by this study.

H3: Physical Obstacles weaken the relationship of social influences and consumption behavior
Based on the above literature review and research hypotheses, the research framework for the present study is shown as Figure 1.

Research and Methodology
In order to test the proposed hypotheses, a carefully constructed questionnaire was employed.A thorough literature review was conducted to identify and adapt items that have been validated in previous research.This was essential to ensure the reliability and validity of the measurement instruments.The items measuring SI and PB were adapted from the work of Venkatesh et al. ( 2012), while items for Trust were based on Yeo et al. (2017), and items for Physical Obstacles were derived from Ali et al. (2020).All items were measured using a 7-point Likert scale (1=strongly disagree, 7=strongly agree).The questionnaire was initially developed in English and subsequently translated into Vietnamese.To ensure cultural and linguistic appropriateness, this translation was subjected to rigorous review to ensure that the meaning and intent of each item were preserved.
The survey was administered over an eight-week period beginning in August 2022.The target population included individuals aged 18 and above who had experience with Online Food Delivery (OFD) services or were familiar with at least one such platform.The survey was made accessible through a Google form link, which allowed participants the flexibility to complete it at their convenience.This approach was conducive to obtaining thoughtful and considered responses.To maximize the response rate, the survey link was disseminated through multiple channels, with a focus on social media platforms such as Facebook, Instagram, and Zalo.A targeted approach was employed to reach specific demographics, including overseas students, by sharing the link on forums and fan pages that cater to this audience.This strategy was instrumental in ensuring a diverse and representative sample.The collected data were was carried out using SPSS and AMOS software.

Respondents' Profile
A total of 378 respondents participated in the study, and the demographic distribution is presented in Table 1.The majority of respondents were male, accounting for 76.64% of the sample, while female respondents constituted 23.54%.The age distribution indicated that most respondents fell within the 18 to 29 age range, comprising 46.56% of the respondents.In terms of education, more than half of the interviewees (51.6%) held a bachelor's degree, constituting the largest proportion.In terms of occupation, a notable proportion engaged in sales and services (30.16%), followed by students at 28%.Moreover, 47.9% of respondents reported an income of "15 million and above".
Regarding the usage frequency of OFD, nearly half (49.4%) of the respondents reported using online food delivery (OFD) services once a week.In terms of accessing online delivery platforms, mobile apps were the most widely used, with 46.56% of the respondents preferring this method.Furthermore, an analysis of the food delivery service providers used by the survey respondents revealed that ShopeeFood (24.3%) and Grabfood (24.1%) emerged as the two most well-known and recognized brands in Vietnam.

Measurement Model
The measurement model analysis consists of two types of validity, namely convergent validity, and discriminant validity.The assessment of convergent analysis is ascertained by examining the loadings, average variance extracted (AVE) and also the composite reliability (Gholami et al, 2013).The loadings were all higher than .50, the composite reliabilities were all above .70and the AVE of all constructs were also higher than .50 as suggested in the literature, as shown in Table 2.In terms of discriminant validity, according to Kline's (2015) suggestion, a correlation coefficient between each of the dimensions of less than .850indicates discriminant validity between the dimensions.Table 2 shows that the correlation coefficients between the dimensions were in the range of .187-.675, satisfying Kline's (2015) requirements for discriminant validity.In addition, according to Hair et al. (2017), if the correlation coefficient for each dimension is less than the root value of the AVE, this indicates good discriminant validity between the dimensions.Table 2 shows that the correlation coefficients for each dimension were less than the root value of the AVE, demonstrating that the dimensions have good discriminant validity.

Structural Model
The results of regression analysis in Table 3 show when the dependent variable was purchase behavior, the unstandardized coefficient B was social influence is .332,showing positive statistical significance (t=3.697,p<.001).This result shows that social influence impacted purchase behavior.Therefore, H1 was supported.The present study employed the method of hierarchical regression analysis, as recommended by Baron and Kenny (1986), to examine the moderation effects as shown in Table 4. Regarding the moderation role of trust, the inclusion of trust as a moderator in Model 2 yielded a significant improvement in predicting the relationship between trust and purchase behavior.The unstandardized B for the interaction term was .103,ΔR 2 =.015 (t=2.667,p<.01), indicating a notable impact of trust as a contextual factor.Therefore, H2 was supported.With regards to the moderating role of physical obstacles, incorporating physical obstacles as a moderator in Model 4 significantly improved the prediction of the relationship between social influence and purchase behavior.The unstandardized B for the interaction term was -.248, ΔR 2 =.077(t= -5.743, p<.001), indicating a substantial enhancement due to the inclusion of physical obstacles as a contextual factor.Therefore, H3 was supported.

Conclusions
The online food delivery (OFD) service industry in Vietnam has witnessed remarkable growth in recent years, driven by technological advancements and evolving consumer behaviors.This study aimed to explore the role of social influence in consumers' adoption and usage of OFD services, considering the moderating effects of trust and physical obstacles, particularly during the COVID-19 pandemic.The findings provide valuable insights into the factors influencing consumers' behavior in the OFD market and have significant implications for industry practitioners and policymakers.
The research findings supported the hypothesis that social influence significantly influences consumers' consumption behavior in the context of OFD services.The positive impact of social influence can be attributed to the reliance on recommendations, peer influence, and social norms in decision-making processes.Consistent with previous studies (Bao & Zhu, 2022;Lee et al, 2019), the results highlight the importance of positive recommendations and social norms in shaping consumers' intentions to adopt and utilize OFD platforms.These findings underscore the significance of social networks and interpersonal relationships in the OFD market, emphasizing the need for businesses to leverage social influence strategies, such as influencer marketing and word-of-mouth campaigns, to enhance their brand reputation and attract more customers.
Moreover, the study revealed that trust plays a crucial moderating role in the relationship between social influence and consumption behavior.Trust in the online platforms and social media recommendations enhances the influence of social factors on consumers' attitudes and intentions.The findings align with prior research on the impact of trust in e-commerce and technology adoption (Qalati et al, 2021;Rehman et al, 2019), highlighting the importance of building trustworthiness and credibility in the OFD industry.Online food delivery platforms should prioritize transparency, reliability, and customer satisfaction to foster trust among their user base.Enhancing trust can further amplify the positive effects of social influence, leading to increased customer loyalty and continued usage of OFD services.
Furthermore, the proposed model for this study incorporates physical obstacles as a moderating variable, specifically in relation to the COVID-19 outbreak.This choice is inspired by the recognition that the pandemic has had a profound impact on consumer behavior, causing significant disruptions to routines and resulting in enduring changes (Koch et al, 2020).The study's findings indicate that physical obstacles weaken the influence of social factors on consumers' behavior.The closure of non-essential stores, the implementation of social distancing measures, and the resulting alterations in individuals' lifestyles have introduced physical barriers to traditional dining experiences, thereby increasing reliance on online food delivery (OFD) services.Tiago and Veiga (2021) emphasize the need for businesses to prepare for future restrictions that may affect their operations.Thus, including physical obstacles as a moderating factor in this study aims to deepen our understanding of the behavior gap within the OFD service environment, with specific attention to the impact of the COVID-19 pandemic.Notably, despite the constraints imposed by the pandemic, social influence remains a significant driver of consumer behavior in the OFD market.These findings accentuate the adaptability and resilience of the OFD industry, which has effectively provided consumers with a safe and convenient alternative during challenging times.
Overall, this study contributes to the existing literature by providing empirical evidence on the influence of social factors, trust, and physical obstacles on consumers' adoption and usage of OFD services.The findings highlight the importance of social influence strategies, the cultivation of trust, and the understanding of contextual factors in the OFD market.Industry practitioners can leverage these insights to develop effective marketing and communication strategies that capitalize on social influence and build trust among consumers.Policymakers can consider these findings when formulating regulations and support mechanisms to facilitate the growth and sustainability of the OFD industry in Vietnam.
However, it is important to acknowledge some limitations of this study.Firstly, the research was conducted exclusively in Vietnam, which restricts the generalizability of the findings to other countries or cultural settings.Therefore, the external validity of the study may be limited.Future research should aim to include a more diverse sample of participants from various cultural backgrounds to enhance the generalizability of the findings.Secondly, the study's focus on the COVID-19 pandemic as a contextual framework may limit the applicability of the findings to non-pandemic periods.As consumer behavior and attitudes can vary across different circumstances, it is important to interpret and apply the findings within the appropriate context.Future research should investigate consumer behavior in the online food delivery (OFD) market during different periods and situations to provide a more comprehensive understanding of the dynamics at play.
To further advance the knowledge in this field, future studies could consider incorporating relevant theories from disciplines such as psychology, sociology, or marketing.Additionally, researchers may explore the inclusion of innovative variables, such as conversion cost, green attitude, or environmental sustainability, to gain deeper insights into the factors influencing consumer behavior or preferences in the OFD market.By expanding the theoretical framework and exploring new variables, researchers can contribute to a more nuanced understanding of the complexities involved in consumer behavior within the context of online food delivery.

Table 1 :
Descriptive Statistics of Respondents

Table 2 :
Reliability, Convergence Validity and Discriminant Validity of Different Factors AVE refers to average variance extracted.The discriminant validity diagonal bold is the root value of AVE, and the lower triangle is Pearson correlation.

Table 3 :
The Impact of Social Influence on Purchase Behavior of OFDS

Table 4 :
The Moderation Effect of Trust and Physical Obstacles