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The virtual supermarket: An innovative research tool to study consumer food purchasing behaviour
© Waterlander et al; licensee BioMed Central Ltd. 2011
Received: 21 January 2011
Accepted: 25 July 2011
Published: 25 July 2011
Economic interventions in the food environment are expected to effectively promote healthier food choices. However, before introducing them on a large scale, it is important to gain insight into the effectiveness of economic interventions and peoples' genuine reactions to price changes. Nonetheless, because of complex implementation issues, studies on price interventions are virtually non-existent. This is especially true for experiments undertaken in a retail setting. We have developed a research tool to study the effects of retail price interventions in a virtual-reality setting: the Virtual Supermarket. This paper aims to inform researchers about the features and utilization of this new software application.
The Virtual Supermarket is a Dutch-developed three-dimensional software application in which study participants can shop in a manner comparable to a real supermarket. The tool can be used to study several food pricing and labelling strategies. The application base can be used to build future extensions and could be translated into, for example, an English-language version. The Virtual Supermarket contains a front-end which is seen by the participants, and a back-end that enables researchers to easily manipulate research conditions. The application keeps track of time spent shopping, number of products purchased, shopping budget, total expenditures and answers on configurable questionnaires. All data is digitally stored and automatically sent to a web server. A pilot study among Dutch consumers (n = 66) revealed that the application accurately collected and stored all data. Results from participant feedback revealed that 83% of the respondents considered the Virtual Supermarket easy to understand and 79% found that their virtual grocery purchases resembled their regular groceries.
The Virtual Supermarket is an innovative research tool with a great potential to assist in gaining insight into food purchasing behaviour. The application can be obtained via an URL and is freely available for academic use. The unique features of the tool include the fact that it enables researchers to easily modify research conditions and in this way study different types of interventions in a retail environment without a complex implementation process. Finally, it also maintains researcher independence and avoids conflicts of interest that may arise from industry collaboration.
The prevalence of overweight and obesity is rising worldwide, with the largest burden among groups with a lower socio-economic status [1–3]. These figures are worrying since overweight and obesity are related to numerous chronic diseases, including type 2 diabetes mellitus, several types of cancer, and cardio vascular diseases . Much research has been conducted in the search for effective interventions which will decrease the prevalence of overweight and obesity. Whereas most of these interventions have been targeted at individual determinants of dietary intake, today it is increasingly recognized that environmental factors also contribute to obesity and that environmental interventions should also be considered .
According to the ANGELO-Framework (Analysis Grid for Environments Linked to Obesity), economic factors are one of the influential environmental factors in food choice . Since there is a large body of evidence showing that currently the healthier choice is the more expensive choice [6, 7], pricing strategies seem a promising intervention to change dietary behaviour, especially for groups with a lower socio-economic status. Both marketing and consumer research have indicated that price is one of the most important tools in steering consumer behaviour [8, 9]. Nonetheless, to date little is known on what the most effective pricing strategy would be. In a previously conducted Delphi Study we examined expert standpoints on what type of pricing strategies would be most feasible and effective in stimulating healthier dietary behaviours. The expert panel agreed on the potential success of offering small gifts, offering price-cuts on healthy foods and discounting healthier foods more frequently . A systematic review of the effectiveness of economic incentives in changing dietary behaviour showed promising results for such strategies indeed . Nevertheless, this review also concluded that the evidence is limited and restricted to small-scaled interventions with a short running period. Examples of such interventions include studies using vending machines or school canteens [12, 13].
While the potential effects of pricing strategies to stimulate healthier food choices are promising, before pricing strategies are introduced on a large scale, information on the effectiveness of such strategies in a broader setting where people obtain most of their groceries is required, that is a retail environment. To our knowledge, the only example of a large-scaled randomized controlled trial on the effects of retail pricing strategies is the New Zealand SHOP study. This study evaluated the effects price reductions of healthier foods (12.5%) and nutrition education on supermarket purchases among 1,104 consumers. The authors found that the pricing intervention alone lead to more healthy food purchases .
As SHOP is the only supermarket trial on food pricing strategies available at present, more research is needed to learn about the actual effects of food pricing strategies. These studies are important complementing those that use data from large datasets (e.g., household expenditure surveys) and thereby gaining insight into complex processes such as 'own-price elasticity' (the change in demand for a product as a consequence of a change in price of that product) and 'cross-price elasticity' (the change in demand for a product in response to a change in the price of another product) . However, such studies are complex, mostly with regard to implementation issues. In order to find a solution to this problem, we developed a research tool which can be used to study the effects of price interventions in a virtual-reality setting: the Virtual Supermarket. This software tool can be used to study various pricing interventions in a supermarket setting without having to rely on a complex implementation process. Below, the development and implementation of this software application will be explained and the results of a pilot study on the effectiveness of the application will be presented.
The front-end of the Virtual Supermarket
After collecting all of their groceries in their shopping cart, consumers in the Virtual Supermarket go to the checkout and, if they have not exceeded their designated budget the application proceeds. If the budget is exceeded, participants are asked to remove some of their groceries. After finishing the shopping task, it is possible to include several configurable questionnaires which the participant must complete before the application transmits the data and closes.
The back-end of the Virtual Supermarket
A key feature of the Virtual Supermarket is that it digitally collects and stores data. The application keeps track of all products purchased by a participant, the time at which the products were selected, the allocated budget, total expenditures and answers to configurable questionnaires. When a respondent completes the virtual shopping task, data is automatically sent to a server and stored in a unique comma-separated value file under the respondent's personal code. The server constantly measures whether it has collected all files. All collected single respondent files can be imported into one Excel data file using a specifically developed web service.
Using the Virtual Supermarket
If researchers are interested in using the Virtual Supermarket for their own research, they can use the information provided in this manuscript and on the projects homepage to find out how the program works. Furthermore, they can download the application to their computer and have a close look into the software. Furthermore, we are also happy to provide the Virtual Supermarket application to other researchers so that they can use it in their own research. The tool is ready to use for Dutch food pricing experiments, but the application was designed in such a way that it can also be used for different types of experiments, such as for example on product placement or supermarket lay out. If researchers are interested, we can provide the software basis, from which they can develop their own Virtual Supermarket. More detailed information about configuration and use of the Virtual Supermarket can be found at the projects' homepage: http://www.bioinformatics.org/supermarket/index.html
Questionnaire on appreciation of the Virtual Supermarket (n = 66)
The program was easy to understand
The products I have purchased in the Virtual Supermarket resemble my regular food purchases
I could easily find my way around the Virtual Supermarket
The Virtual Supermarket contained sufficient product variety
There were sufficient choice options in the Virtual Supermarket
The stock of the Virtual Supermarket is a fair representation of the stock of a real supermarket
I could relatively easily find all the products in the Virtual Supermarket
I was able to imagine doing my real-life grocery shopping in the Virtual Supermarket
Participant characteristics Pilot Study (n = 66)
Level of responsibility for groceries in real life
Shared responsibility with partner
Weekly budget for groceries in real life (€)
The Virtual Supermarket is a three-dimensional web-based software application which was designed to simulate a real supermarket. Unique features of the tool include that it enables researchers to easily modify research conditions (e.g., different pricing or labelling strategies) and in this way study different types of environmental interventions that might stimulate healthy eating without having to rely on a complex implementation process. Although the Virtual Supermarket can never replace studies in a real-life setting, it is an innovative research tool with great potential to assist in gaining further insight into consumer behaviour.
The Virtual Supermarket was pilot-tested among n = 66 consumers. This study revealed that a large majority of the participants found the program easy to understand and indicated that their virtual purchases largely corresponded to their groceries in real life. On the basis of this pilot study it can be concluded that the Virtual Supermarket is a useful tool for studying consumer food purchasing behaviour. A limitation of the pilot study was that it did not include age measurements. Age may be of importance since younger participants may find it easier to work with a computerized program than older participants. However, a growing number of people have access to a computer and computerized tools are even used in studies specifically aimed at older adults . Based on this, it is not expected that the workability of the Virtual Supermarket is rated differently among different age groups. Nevertheless, during recruitment we made an effort to include participants from different age groups and focused on middle-aged people. Another limitation of the pilot study is that the number of participants may be considered low. However, we included participants with varying education levels and backgrounds and therefore believe the pilot study offers a fair impression of how the Virtual Supermarket is perceived among the general public.
The Virtual Supermarket is a valuable tool precisely because it offers high levels of controllability, it allows prices to be easily be manipulated, and because a complex implementation in a real-life setting is avoided. Nevertheless, the feasibility of interventions in real life settings should not be neglected . Behaviour in a real setting may differ from a virtual setting because real life concerns real money and real products and this may lead virtual shopping to be taken less seriously. It is therefore of major importance to validate the Virtual Supermarket against real-life food purchases. At the moment, we are planning such a validation study. As the Virtual Supermarket has not yet been validated against actual food purchases, this is a major limitation which should be considered when applying the tool for research. At the same time, however, electronic shopping is becoming increasingly common these days, and a large majority of participants in the Virtual Supermarket study indicated that their virtual groceries resembled their normal groceries. Moreover, there is evidence that peoples' virtual behavior largely corresponds with their actual behavior. Sharpe et al. (2008) validated food and beverage choices made in a virtual road trip survey by comparing those choices with choices made in a real McDonalds a week later. The authors concluded that peoples' simulated purchasing behavior is highly predictive of their real behavior . Virtual shopping behaviour may thus also be fairly comparable to real-life shopping behaviour.
A second limitation of the Virtual Supermarket is the product selection procedure. Due to feasibility issues we had to decrease the usual supermarket stock of thousands of products to 512 products in the Virtual Supermarket. This was undertaken by the researchers and not based on sales data. Due to this process some popular products may be not available in the Virtual Supermarket and people were limited in the number of choices. The tool may therefore not give a complete picture of complex phenomena such as product selection within food categories and the cross price elasticity of demand . Nevertheless, the application presents a representative sample of the stock of an average supermarket and contains a fair number of products from all product categories (for example, 19 types of cheese, 20 types of chocolate and 41 types of vegetables). Also, a majority of the participants indicated that the Virtual Supermarket had sufficient choice options. Furthermore, because the application has the features of a real supermarket, it may provide better quality predictions than experiments using small-scaled settings such as vending machines or laboratory settings. To our knowledge, there are no other software tools available comparable to the Virtual Supermarket. While there are some examples, they have the appearance of a web shop, where products can be selected through product lists . In addition, there are examples of supermarkets in a laboratory setting, such as that of Epstein et al. . A major limitation of this laboratory setting is that the number of products is very limited (around 60) and not all food categories are represented. The Virtual Supermarket is unique in that it is a three-dimensional software application in which the shopping experience closely resembles that of a real supermarket. Moreover, alongside the features described, the Virtual Supermarket can be adapted for future studies by placing other products of interest in the supermarket, that is different brands of products or products that fit the dietary patterns of other countries.
A final remark on the current version of the Virtual Supermarket concerns the fact that the application is based on a Dutch supermarket which means that it can not be used in other countries without some adaptations. However, the software is constructed in such a way that complex alterations are possible. The application base can be used to build future versions. Also, we are currently working with SARA on developing an English-language version of the Virtual Supermarket.
Pricing strategies are frequently cited as a promising tool to stimulate healthier food choices. However, experimental evidence on the effectiveness of such strategies is limited. This lack is merely due to the complex nature of good-quality pricing experiments in larger food environments such as supermarkets. In order to find a solution to this problem, we designed a unique research tool: the Virtual Supermarket. The Virtual Supermarket is a three dimensional software application which was designed based on a real supermarket. A pilot study among n = 66 participants revealed that the application stores data accurately and is rated well by its users. The participants had no trouble understanding the application and reported that the purchases they made in the Virtual Supermarket were similar to their real-life purchases. Although the Virtual Supermarket can never replace studies in a real-life setting, it is an innovative research tool with a great potential to assist in gaining further insight into consumer behaviour.
Availability and requirements
Project name: The Virtual Supermarket
Project home page: Detailed information about the Virtual Supermarket application, downloads and configuration can be found at: http://www.bioinformatics.org/supermarket/index.html.
The application can be downloaded for: Windows: http://www.falw.vu/boodschappen/Supermarket_0027_windows.zip; Mac: http://www.falw.vu/boodschappen/Supermarket_0027_mac_universal.zip. The installation consists of unpacking a compressed file to the desired location.
Operating systems: Windows, Mac
Programming language: Not applicable. The application was developed in Unity which is both a game engine and a game development environment. Changes with respect to research conditions (e.g., pricing, signage, etc.) can be made using a text editor. How this works is described at the projects' homepage
Other requirements: Not applicable
Licence: The application can be obtained for free for academic purposes without any further agreements.
Any restrictions to use by non-academics: The application in its current form may not be used for commercial purposes. Before using the application, non-academics should contact us via email@example.com or firstname.lastname@example.org.
a SARA is the Dutch National High Performance Computing and e-Science Support Centre, and the Dutch supernode in the international Science Grid. SARA collaborates with the VU University Amsterdam on a non-profit base.
We would like to thank Tijs de Kler from SARA Computing and Networking Services for his invaluable assistance in the final stages of the development of the Virtual Supermarket as well as his valuable comments on the manuscript. This work was supported by a grant from the Netherlands Organization for Health Research and Development (ZonMw)-project number: 50-50105-96-426-and a special Software Development Fund of VU University Amsterdam which is dedicated to SARA Computing and Networking Services Amsterdam for use in the development of new scientific software tools (VU-SARA collaboration).
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