The Impact of Marketing Mix Elements on Food Buying Behavior : A Study of Supermarket Consumers in Vietnam The

The purpose of this study is to investigate the impact of marketing mix elements on food buying behavior of supermarket consumers in Vietnam. Empirical evidence from 222 participants shopping at five supermarkets validates a theoretical model, indicating a significant positive relationship between marketing mix variables and food purchasing behavior. Results reveal that product factor exerts greatest influence on consumer buying decision, followed by shopping convenience, store atmosphere, price, promotion and personnel respectively. These findings contribute to the literature relating to retail marketing and have marketing implications for bringing traffic into supermarkets and increasing sales.


Introduction
Scholars substantially identify marketing mix as controllable parameters that firms use to influence consumer buying process (Brassington & Pettitt, 2005;Kotler, 2010).The conventional framework of marketing mix comprises 4Ps: product, price, place and promotion (see review in Waterschoot & Van Den Bulte, 1992).As the marketing literature evolves the 4Ps mix has been adapted to various domains, including retail marketing (Constantinides, 2006).Embracing both services and relationship marketing theories, retail marketing scholars have extended the 4Ps through the inclusion of elements such as store environment, personnel, store formats and physical evidence (Baker, Parasuraman, Grewal, & Voss, 2002;Mulhern, 1997).In the context of food retailing, a growing volume of studies reveal that conventional marketing mix elements such as product's quality and package, price, store location and promotional tools shape consumer buying behavior (e.g., Akbay & Jones, 2005;Knight, Jackson, Bain, & Eldemire-Shearer, 2003;Nevin & Suzan Seren, 2010;Spinks & Bose, 2002).Also, consumers increasingly pay attention to store environment factors including atmosphere and personnel when shopping at supermarkets (Nevin & Suzan Seren, 2010;Turley & Milliman, 2000).Such elements influence customer perceived value and purchasing decisions towards food products (Chaudhuri & Ligas, 2009).Despite extensive research efforts, there is a paucity of knowledge relating to retail marketing and food buying behavior in emerging markets, especially in Vietnam.
The food retail industry in Vietnam is considered to be a competitive, dynamic sector which has the projected annual growth of six percent for the 2013 to 2018 period (Euromonitor International, 2014b).Despite the dominance of traditional channels in the retail market, modern retailers (e.g.supermarkets, hypermarkets, convenience stores and department stores) are expanding to tailor urban consumers' demands (Tyng & Truong, 2013).Notably, participation of international players and young consumerism has driven the rapid expansion of supermarkets (Hai Thi Hong, Steve, & Neil, 2013).Food products are currently sold at 431 supermarkets nationwide (Euromonitor International, 2014b).Given the fierce competition in the sector, supermarkets seek to improve the effectiveness of their marketing programs aimed at generating and increasing consumer demands.Hence, understanding the impact of marketing mix variables on Vietnamese consumers' purchase of food products is of paramount importance for supermarkets.
Taking into account of these considerations, this study attempts to investigate the impact of marketing mix elements on food buying behavior of supermarket consumers in the context of Vietnam.Specifically, the objectives are twofold: (1) to examine the relationship between marketing mix variables and food purchasing behavior; and (2) to identify which elements exert greatest influence on food buying decision of Vietnamese supermarket consumers.
In the next section, this study develops a theoretical framework and research hypotheses based on the literature relating to retail marketing mix and food buying behavior.Subsequently, research method and results are discussed.This is followed by conclusion and marketing implications.Finally, future research directions are presented.

Theoretical Framework and Hypothesis Development
Researchers propose different frameworks of retail marketing mix.For example, Dunne et al. (2010) suggest that key marketing elements in retailing include merchandise, price, advertising and promotion, customer services, store layout and design and people while Kotler and Keller (2009) argue for an integrative approach, indicating that store retailers' marketing decisions involve target market, product assortment, services provided by personnel, store atmosphere, price, promotion and place.This study particularly focuses on six common elements of retail marketing mix, namely product, price, place (convenience), promotion, store atmosphere and personnel.

Product
Product quality shapes retailers' reputation and influences consumer buying decision at stores (Pan & Zinkhan, 2006).Chaudhuri and Ligas (2009) suggest that product value is positively correlated to purchase behavior and customer loyalty in the retail sector.Consumers evaluate various dimensions of food products to make their purchase decision.Nevin and Suzan Seren (2010) reveal that Turkish consumers are concerned about food nutrition and safety when shopping at supermarket.Spinks and Bose (2002), in a study of seafood purchasing in New Zealand, find that consumer decision is influenced by product characteristics of nutrition, taste, health benefit and ease of preparation.Additionally, Maruyama and Trung (2007) demonstrate that the underlying reasons for buying fresh food in Vietnamese supermarkets include factors such as brand names, ranges of size and volume, the freshness and the origin of goods.Recently, scholars typically identify food label and package as important determinants of consumer purchasing decision (Akbay & Jones, 2005;Andreas, Panagiotis, & Rodolfo, 2007;Jabir, Sanjeev, & Janakiraman, 2010;Jean & Louis, 2011;Kempen, Bosman, Bouwer, Klein, & van der Merwe, 2011).Hence the following hypothesis has been developed: H1: Product factor has a positive influence on consumer buying behavior.

Price
French (2003) indicates that food pricing is an essential factor that shapes individual choice.Given the importance of cost saving consumers evaluate and compare price during the process of food purchasing (Nevin & Suzan Seren, 2010).Conventional wisdom indicates that, a high retail price which reflects immediate monetary costs are likely to hinder consumer purchase behavior while a low price or competitive price leads to an increase in store traffic and product sales (Barbara, Lois, & Bobby, 1996;Pan & Zinkhan, 2006).Interestingly, some authors challenge this view and argue that consumers who seek to maximize expected quality are willing to pay for the highest-priced products (Dodds, Monroe, & Grewal, 1991;Kerin, Jain, & Howard, 1992).That is, consumers are interested in the ratio between price and quality when making purchase decision.Figuié and Moustier (2009) find that most of Vietnamese supermarket consumers perceive high price as an indicator of product quality.In general, empirical studies find that competitive and reduced prices promote the purchase of food in retail stores (e.g., French et al., 1997;Hansen, 2003;Jeffery, French, Raether, & Baxter, 1994).Hence the following hypothesis has been formulated: H2: Competitive price has a positive influence on consumer buying behavior.

Place/Convenience
Place decision involves activities that make products available to target customers (Kotler & Keller, 2009).As such, it aims to provide shopping convenience sought by consumers in modern retail channels (Pan & Zinkhan, 2006).Most researchers agree that a convenient location increase store patronage via reduced transaction costs (Berry, Seiders, & Grewal, 2002;Huddleston, Whipple, & VanAuken, 2004;Jabir et al., 2010).The central place theory (Craig, Ghosh, & McLafferty, 1984) posits that retail stores at central locations may attract consumers from long distances.Alongside location, results of an India study (Jabir et al., 2010) show that food consumers prefer supermarkets which have longer opening hours, sufficient parking, product availability and accessibility.One interpretation could be that these elements altogether create consumers' perception of service quality provided by retailers (Berry et al., 2002;Chaudhuri & Ligas, 2009;Pan & Zinkhan, 2006).Empirical evidence confirms that convenience significantly affects consumer purchase of food products (Jaravaza & Chitando, 2013;Maruyama & Trung, 2007).Hence the following has been hypothesized: H3: Shopping convenience has a positive influence on consumer buying behavior.

Promotion
Promotion is a marketing activity that retailers use to bring traffic into stores and generate sales by communicating current offerings to targeted consumers (Dunne et al., 2010, p. 392).Specifically, promotion can increase sales through sales switched from other stores and increase in consumption from existing consumers (Ailawadi, Harlam, César, & Trounce, 2006).Dunne et al. (2010) propose four basic types of promotion: advertising, sales promotions, publicity and personal selling.Two unique tools that create differences between retailer and manufacturer promotional programs include in-store sales promotion and advertising (Bemmaor & Mouchoux, 1991).A Chinese study (McNeill, 2006) reveals that consumers pay great attention to sales promotion (e.g.free gift, sampling, loyalty programs, discounts, and coupon) when selecting stores.This finding is extended by Hansen (2003) who demonstrates that promotional tools such as print advertisements, direct mail, customer loyalty and discount are likely to attract consumers to retail stores, leading to their purchase.Interestingly, Maruyama and Trung (2007) find that in-store advertising (e.g.panel, billboards, and flyers) has strong potential in affecting Vietnamese consumers' purchasing decision toward food products.Hence the following hypothesis has been developed: H4: Promotion factor has a positive influence on consumer buying behavior.

Store Atmosphere
Retailers seek to plan and change their stores' physical surrounding or environmental cues to influence shopping behavior of patrons (Bitner, 1992).Store atmosphere (environment) drives pleasure, time and money spent and number of items purchased (Donovan, Rossiter, Marcoolyn, & Nesdale, 1994;Sherman, Mathur, & Smith, 1997).Berman and Evans (2013) categorize atmospheric stimuli into four groups, namely the exterior, the general interior, the layout and design factors, and the point-of-purchase factors.This current study focuses on the general interior which consists of elements such as lighting, color schemes, scents, music, temperature and cleanliness.Milliman (1982Milliman ( , 1986) reveals that music background affects purchase and length of stay of supermarket shoppers and restaurant patrons.A study of retail atmospherics (Sharma & Stafford, 2000) proves that cleanliness and attractiveness affect consumer intention to purchase products.Turley and Milliman (2000), in a review of previous experimental studies, demonstrate that odor and lighting significantly influence shopping behavior.Hence the following has been hypothesized: H5: Store atmosphere has a positive influence on consumer buying behavior.

Personnel
Personnel appear to be central to creating store shopping experience through interaction with targeted customers (Kerin et al., 1992).As salespeople are the main forces that directly contact with shoppers they are capable in screening, counseling and convincing consumers to purchase products (Dunne et al., 2010).Human factors are identified as strategic elements that have strong impact on purchasing behavior and store sales (Turley & Chebat, 2002).Empirical evidence proves that consumer buying decision is influenced by employees' knowledge, friendliness and support (Baker, Grewal, & Parasuraman, 1994;Baker et al., 2002;Sharma & Stafford, 2000).Hu and Jasper (2006) stress that helpful and supportive staffs create perceived service quality which consequently leads to consumers' purchase intention.Similarly, Maruyama and Trung (2007) demonstrate that quality staffs reflect professional services which facilitate consumers to experience modern shopping style when buying products at Vietnamese supermarkets.Hence the following hypothesis has been formulated: H6: Personnel factor has a positive influence on consumer buying behavior.
Based on the critical review of literature, a theoretical framework was proposed (Figure 1).The framework illustrates the relationship between six elements of retail marketing mix and consumer buying behavior.
Figure 1.The proposed research model

Research Design
This study employed a deductive and quantitative approach (Saunders, Lewis, & Thornhill, 2012).This facilitated investigating the impact of marketing mix elements on food purchasing behavior based on existing research.Quantitative data was collected by paper-based surveys in Hanoi, Vietnam.Given that food purchasing behavior varies across categories and measurements, this study focus on the actual purchase of a specific category, namely frozen food.The category is selected for two reasons.Firstly, frozen food has received less attention from researchers in comparison with organic and fresh food (e.g., Glitsch, 2000;Hughner, McDonagh, Prothero, Shultz, & Stanton, 2007;Michaelidou & Hassan, 2008).Secondly, frozen food products are increasingly purchased and consumed by Vietnamese supermarket shoppers (Euromonitor International, 2014b).Therefore, the study population is Vietnamese consumers who have purchased frozen food at supermarkets located in Hanoi within the last month.

Survey Instrument
A survey instrument was developed based on selection and adaptation of existing validated scales in the literature relating to retail marketing mix and food purchasing behavior.Table 1 describes how the constructs were operationalized and corresponding references.All the independent variables were measured by a 5-point Likert scale indicating consumers' perceptions on various marketing mix elements.The buying behavior variable was measured by purchase frequency and money spent on frozen food during the previous month.As consumers generally struggle to provide the exact money spent, responses were organized in appropriate categories (Ajzen, 2002).
A pre-test of the questionnaire was conducted to diagnose and eliminate potential problems associated with the questions.Using the cognitive interviewing method (Presser et al., 2004), the researchers performed ten in-depth interviews with marketing experts and frozen food consumers.Four marketing experts were asked to present their comments on the efficacy of the items and scales used in the survey, which helps to ensure the content validity (Saunders et al., 2012).In the following interviews, each of six food consumers was asked to complete the survey in the researcher's presence and then to verbalize their thoughts on key issues such as time to complete the survey, the clarity of instructions, question wording and questionnaire layout (Bell, 2010).This process helped to clarify the survey's face validity (Saunders et al., 2012).Based on interviewees' opinions, modification was made to ensure that items were appropriate for all participants.The final survey instrument contained a screening question and three main sections, including questions measuring buying behavior, marketing mix factors and consumer profile.

Data Collection
Paper based copies of the survey instrument were randomly distributed at five supermarkets in Hanoi.More specifically, one in three consumers entering the supermarket was asked to participate in the research.Consumers who met the recruitment criteria and agreed to respond received the survey and a self-addressed envelope affixed with postage stamp so that they can mail the completed instrument back to the researchers.The duration of survey delivery and collection was four weeks.A total of 430 surveys were distributed and 259 questionnaires were returned.As there were 37 inappropriate surveys the effective sample size of this study was 222.

Participant Profile
Table 2 exhibited characteristics of the sample based on key demographic factors.The gender analysis showed that most of the participants were female representing 76.1 per cent of the sample and 23.9 per cent were male.These figures indicated that females were responsible for purchasing frozen food in the household.The age statistics showed that 32.0 per cent of the participants were less than 27 years followed by the group of 28-30 years representing 25.7 per cent of the sample.Regarding the family income, a total of 41.4 per cent of the participants had family income under VND10,000,000 per month while only 15.4 per cent had family monthly income over VND20,000,000.Overall, the main consumers of frozen food products were young women with relatively limited budget; hence they would be likely to carefully consider product offerings to maximize expected value when making purchasing decision.

Reliability
The reliability of measurement was assessed by examining the Cronbach's Alpha, which measures internal consistency of reliability (Hair, Black, Babin, Anderson, & Tatham, 2006).A Cronbach's Alpha above 0.7 is considered acceptable for most research objectives (Allen & Bennett, 2012).Table 3 showed that the Cronbach's Alpha for research variables ranged from 0.737 to 0.922, which suggest good internal consistency of measurement scales.

Hypothesis Testing
In a first step, bivariate correlations were computed to analyze the proposed relations between variables.The Pearson's correlation coefficients confirmed significant positive associations between the predictors and the dependent variable.Next, a multiple regression was done to investigate the relative impact of marketing mix elements on buying behavior.The results of the regression were illustrated in the table below.Prior to interpreting the results, regression assumptions were checked (Field, 2009).Firstly, the boxplots and histograms showed that each variable was normally distributed and free from outliers.Secondly, the partial plots and scatterplots indicated that the assumptions of linearity and homoscedasticity were met (Allen & Bennett, 2012).Thirdly, multicollinearity was evaluated by using the tolerance value and the variance inflation factor (VIF).The statistics showed that each variable had a tolerance value of more than 0.40 and a VIF of less than ten, hence multicollinearity would not interfere the outcome of multiple regression analysis (Field, 2009;Hair et al., 2006).

Discussion and Conclusion
Overall, this study provides insights into consumers' perception on retail marketing mix elements and how these factors influence their buying behavior.The multiple regression analysis confirms a significant positive relationship between marketing mix variables and consumers' actual purchase of frozen food.Specifically, the results show that product is the most important factor that affects consumer purchase decision towards the frozen food purchase followed by shopping convenience, atmosphere, competitive price, promotion and personnel respectively.Regarding product attributes, consumers pay great attention to nutrition and variety.Also, they are interested in well-known brand and attractive and informative package.The results are consistent with findings in studies of food buying behavior in Turkey (Nevin & Suzan Seren, 2010), in India (Jabir et al., 2010) and Denmark (Hansen, 2003).Shopping convenience (convenient location, long opening hours, accessibility and large parking area) and store atmosphere (cleanliness, color schemes, music, lighting and scents) increase consumers' purchase frequency and money spent on frozen food products.The results support argument of authors (e.g., Berry et al., 2002;Jabir et al., 2010;Jaravaza & Chitando, 2013;Sharma & Stafford, 2000) that consumer buying behavior is driven by convenience orientation and comfortable atmospherics.Interestingly, Vietnamese supermarket consumers are less concerned about price and promotion.Two possible interrelated explanations include that Vietnamese consumers increasingly prefer healthy food and that they are willingness to spend more on high-quality product for their families and children (Euromonitor International, 2014a).Additionally, Figuié and Moustier (2009, p. 213) demonstrate that supermarkets are not perceived as intended for low-income households and Vietnamese consumers believe that higher price represents better food quality.Finally, personnel factors such as friendliness, support and knowledge exert lowest influence on consumer buying behavior.It could be an effect of the previously mentioned result that consumers prefer to search information on products' package and label.

Marketing Implications
This study suggests that supermarkets should attempt to develop effective marketing mix, with a specific focus on the three most influential factors of product, convenience and atmosphere, to increase store traffics and generate sales from targeted consumers.Key marketing implications are presented as follows:  Product category: Supermarkets should seek to frozen food category with regard to product types and package sets.Also, focusing on health benefits (e.g.nutrition, safety, and reliability) would increase sales and maintain customer loyalty.Such benefits should be communicated clearly via attractive packages providing important information about quality certification, hygiene standard and nutrition.
 Shopping convenience: There is indeed a need for supermarkets to provide shopping convenient through convenient location, easy accessibility, large parking area and longer opening hours.Opening and expanding stores at central locations would reduce consumers' transaction costs that consequently facilitate purchases.
 Store atmosphere: Supermarkets should focus on designing a comfortable atmosphere through cleanliness, appropriate scents and temperature, attractive color and lighting.Doing so would improve store image that influences retail patronage and sales.
 Other marketing variables: Price should be carefully set to reflect corresponding quality of products.Given the increasing competition in the food retailing sector, price reductions and sales promotion (e.g.voucher, coupon and loyalty program) could be effective in increasing demand of certain segments such as students and blue collar workers.Furthermore, enhancing effective interaction with shoppers through supportive and competent employees would be beneficial in the long term.

Future Research
Although this study has produced significant results it is not without limitations.Notably, the research focused only on retail marketing variables.Future research should incorporate personal factors (e.g.demographics and psychographics) and macro environment stimuli (e.g. economic and socio-cultural variables) to explain consumer purchasing behavior.Also, the survey was administered to a relatively small number of respondents; hence there would be a need for bigger sample size.Finally, data collection in different geographic areas would be useful for increasing sample representativeness and clarifying regional differences in consumers' purchase behavior towards frozen food

Table 2 .
Participant profile based on selected demographic factors

Table 4 .
Results of multiple regression analysis