Sampling Technique

Previous research (Australian Trade Commission 2010; Rangkuti and Slette 2010; KPMG 2006; Kamath and Godin 2001) have also suggested that there are distinct differences between consumers who shop at traditional wet markets and those who shop at modern supermarkets and hypermarkets. The preliminary results of this study demonstrated that the majority of consumers exhibited cross-shopping behaviour across modern and traditional retail food stores. More specifically, the majority of consumers exhibit selective adoption behaviour, as they mostly purchase fresh food from traditional wet markets and dry and durable food from modern retailers (mainly hypermarkets).

In a situation where the researcher needs to focus on a specific group of the population, a stratified sample may be considered more suitable than a simple random sample (Zikmund et al. 2011). In this method of sampling, after the population has been divided into different homogeneous groups (strata) based on some sample characteristics, the researcher randomly selects samples from each of the strata (Fink 2013; Mooi and Sarstedt 2011; Zikmund et al.

2011).

Consumer populations may be stratified by gender (Thompson 2012; Zikmund et al. 2011;

Allison et al. 1996), by age (Allison et al. 1996), by geographic region or socioeconomic factors (Thompson 2012). The survey locations were selected to minimize the potential confounding effects of location: it is well known that the place or region of residence is often associated with a number of other socioeconomic indicators. For example, Johnston, Rodney and Szabo (2012) concluded that consumers in different cities and neighbourhoods exhibit specific ways of consuming. Stewart et al. (2004, cited in Mehmood & Rehman 2010) also suggested that region or location influenced consumers’ decision-making. This in turn may relate to similarities in infrastructure access and location-related lifestyle attributes (Fan et al. 2007). For this study, the consumer survey was conducted in Pekanbaru City to make sure that the respondents had access to both traditional wet markets and hypermarkets.

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The main steps involved in selecting a random sample are to: (1) define the target population; (2) develop a sampling frame; (3) choose a sampling technique; (4) determine the minimum sample size; and (5) decide on how to generalize sample data to the general population (Collis and Hussey 2009).

Researchers do not always have an accurate list available from which to select respondents (Zikmund et al. 2011). In this study, as a sampling frame – a list of the population members – was not available, the chosen alternative was to select the sample by interviewing every n^th consumer passing a point in a survey location (Stevens et al. 2006). Then structured questionnaires were administered in this study through a shopping mall-intercept technique.

A shopping mall intercept is considered the most appropriate sampling to achieve the research objectives in the field of consumer shopping habits and consumer behaviour (Delgado-Ballester, Hernandez-Espallardo and Rodriguez-Orejuela 2014), as the respondents are able to better relate to the research topics in a food shopping environment (Sweetin et al.

2013, cited in Phau, Huimin and Chuah 2015). However, as not all households in the survey area has an equal chance of being interviewed, some researcher categorized mall-intercept technique as non-probability (convenience) sampling (Argan, Argan and Akyildiz 2014) or quasi-random sampling (Cheah et al. 2015; Delgado-Ballester, Hernandez-Espallardo and Rodriguez-Orejuela 2014).

On the other hand, other scholars consider mall-intercept technique as one type of random sampling method. According to Hair, Bush and Ortinau (2003), this alternative person-administered interview (often called a shopping mall-intercept interview), where mall shoppers are randomly stopped and asked to participate. This procedure is considered to be the most appropriate for collecting shoppers’ data (Jamal et al. 2006) and for capturing the characteristics of the shopper population (Farrag, El Sayed and Belk 2010).

FAO (2016) clarifies that mall-intercept method is classified as non-probability (purposive) sampling when respondents were non-randomly selected based on a pre-defined fixed quota.

The example of this non probability mall-intercept was applied by Levy, Fein and Schucker (1996), where they set the quotas for shoppers at eight shopping malls based on age, race, income and education in their study about food labeling. This study, however, did not set quota based on demographics but focussed on the coverage of shoppers at both modern and traditional food retailers. Therefore, this study applied mall-intercept (interval) sampling which has been widely used in consumer studies from both hypermarkets and traditional wet

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markets and the use of interval of every n^th shopper was applied as a means of averting sample bias.

Shopping mall-intercept interviews generally gain access to potential respondents within a short period of time, and are widely used in consumer marketing research (Jayasankaraprasad and Kathyayani 2014; Macharia, Collins and Sun 2013; Khare 2011;

Prasad and Aryasri 2011; Bai, Wahl and McCluskey 2008; Domínguez 2007; Ou, Abratt and Dion 2006; Grace and O'Cass 2005; Reynolds, Ganesh and Luckett 2002). This technique shares the advantages of an in-home interview; however it is less expensive and less effort is needed to secure participation, because the interviewer and the potential respondents are already at the same location (Hair, Bush and Ortinau 2003). However, shopping mall-intercept surveys also have some limitations: (1) the respondents may often be in a hurry, and therefore may respond in a careless manner; and (2) respondents may shop with family or friends, which may influence how they answer the questions (Gates and Solomon 1982, cited in Bush and Parasuraman 1984). The main concern here is the inability to generalize results to the target population (Hair, Bush and Ortinau 2003; Murry, Lastovicka and Bhalla 1989). This lack of representativeness, or selection error, is due to the following: (1) mall patrons may not represent the population of interest; (2) mall patrons are usually selected from mall traffic using quota sampling, where enumerators tend to select respondents based on similarity or availability (Zikmund et al. 2011; Murry, Lastovicka and Bhalla 1989); and (3) if the interviews take place in areas other than the entrance area, or take place in street markets with no clear entry or exit area, people who stay longer in the mall have a greater chance of being selected, causing length-biased sampling (Nowell and Stanley 1991).

In spite of these concerns, Joseph and Soundararajan (2009) suggest that shopping mall-intercept interviews are reliable and easy to implement. This type of interview has an advantage over surveys conducted in respondents’ places of residence, because it is difficult to track households that have purchased items from certain retailers. Bush and Grant (1995) suggested that shopping mall-intercept was the most suitable approach to consumer survey;

however, they also commented that market researchers should be cautious of omitting or under-representing some subgroups in the sample.

To reduce interviewer selection bias, a systematic sampling procedure to solicit every n^th person in a specified area such as the mall entrance was applied (Mortimer and Clarke 2011;

Hornik and Ellis 1988). In this study, every fifth consumer entering the outlet was approached to participate in the survey (Chamhuri 2011; Mortimer and Clarke 2011; Joseph and Soundararajan 2009). If the targeted individual was not eligible or refused to participate,

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the individual was replaced with the next eligible consumer. In situations in which there were not many consumers visiting a sampled food retailer (wet market or hypermarket), every alternate consumer who shopped the retail outlet was approached.

Given the objective of this study to gain insights on consumers’ cross-shopping behaviour between modern and traditional food retail stores, this study employed systematic interval sampling from both type of food retailers to ensure that similar numbers of respondents will be drawn from both the traditional wet markets and modern hypermarkets.

Most hypermarkets are located within a shopping mall complex: in Pekanbaru City, only one hypermarket (Lottemart) stands on its own. Furthermore, to eliminate any temporal effects, all four wet markets were chosen based on their close proximity to each of the four hypermarkets. Surveys were conducted simultaneously in one modern retail store and its adjacent traditional wet market each week for a duration of five weeks (see Table 6.1).

155 Table 6.1: Survey time and location of survey

Week Day Hypermarkets Suburb Wet markets Suburb

1 21/01/13 to

Tampan Arengka 7 days Tampan

3 04/02/13 to

Payung Sekaki Kodim 3 days Senapelan

Hypermart SKA

Tampan Kodim 7 days Senapelan

5 18/02/13 to

Payung Sekaki Arengka 1 day Tampan

Loket 1 day Sukajadi