Towards Sustainable Private Labels—What is the Consumer Behavior Relating to Private Labels in the UK and Poland?

Consumer behavior towards private labels (PLs) is constantly changing, accompanied by the development from generic products, offered at very low prices, towards sustainable PLs. Our study aimed to analyze the behavior of British and Polish consumers towards PLs of the retail chains. To achieve this, special attention was given to the following issues: frequency of purchasing PLs by food categories, motives for purchasing PL products, opinions of the current development of PLs, and length of the period of purchasing products under PLs. We also presented the socioeconomic features of the Polish and British consumers purchasing PL products using a correspondence graph. Our research was conducted using a sample of 500 adults from Poland and 500 adults from the UK and the Computer-Assisted Web Interviewing method (CAWI) was used. The questionnaire was addressed only to adults who declared that they purchase PL products. For a detailed analysis of consumer choices and service quality assessment, we used Pearson’s chi-square test, as well as the Kohonen’s neural network and multi-dimensional cluster analysis. We have divided the sample population into 4 clusters based on 6 factors, characterizing households: education level, income, household residence, age, gender, and period of buying PL products. Our study indicates that Polish consumers are more likely to pay attention to lower prices for PLs, while British consumers point quality compared to manufacturers’ brands. In the opinion of Polish consumers, an improvement in quality is only just beginning. This means that PLs available on the British market are characterized by a higher stage of development towards sustainable PLs.


Introduction
Consumer attitudes towards private labels (PLs) have changed significantly in recent years [1][2][3], with the development of PLs. Initially, PLs were treated as a cheap and low-cost substitute, [4] of acceptable, but low quality [5,6] being an alternative to the producer's brand [4]. Currently, PLs as products of comparable or even higher quality than national brands are purchased not only by highly price-sensitive customers [5,6]. It provides an opportunity for retail chains to develop sustainable PLs [7].
Products categorized as PLs are produced, distributed, and sold under a retailer's brand, which may be the retailer's name or a name used exclusively [8] as well as the retailer umbrella brand [9,10]. Private Label Manufacturer's Association (PLMA) has defined PL as a product that encompasses all merchandise sold under a retailer's brand. Many PLs are owned and marketed by retailers under their store brand name or a new brand name [4]. According to Nielsen's Report, a new retail revolution in the development of PL products is currently taking place [11]. This is since PLs have established market position as branded products and compete with leading producer and national brands in terms of quality [12] and sustainability [7]. Retailers are introducing PLs to all segments, from premium to the Therefore, our study aimed to analyze the behavior of British and Polish consumers towards PL products. We have analyzed five issues such as frequency of purchasing PLs by food product category, motives for purchasing products offered under PLs, consumers' opinions on PL development, and length of the period of purchasing products under PLs. Special attention has been paid to the motives for purchasing products offered under PLs and consumers' opinions on PL development, which indicates the PL development towards sustainable PLs. We also presented the socioeconomic features of Polish and British consumers purchasing PLs products using a correspondence graph. This is another stage of the authors' research. So far the Polish market has been analyzed concerning motives of PLs' purchasing [36][37][38]; knowledge and understanding of PLs' concept [36][37][38]; purchase portfolio of PLs [11,39]; strategies of PLs in the discount retail chain [33]; and the evolution of PLs and retail trade in Poland over the last 20 years [37,40,41].

Ethics Approval Statement
The study was conducted according to the guidelines of the Declaration of Helsinki [42]. The study protocol was approved by the Ethics Committee of the Faculty of Human Nutrition and Consumer Sciences of the Warsaw University of Life Sciences (No. 46/2017; 18.12.2017). All the participants provided their informed consent prior to participating in the research.

Data Collection
Our research was conducted on a sample of 500 adults from Poland as well as 500 adults from the UK in January 2018. We used the Computer-Assisted Web Interviewing method (CAWI), which is one of the methods in quantitative research in social sciences [43]. The questionnaires were filled by respondents in the on-line mode with the use of the communication medium in the form of the Internet network. It enables the data to be collected quickly and easily, especially for large samples in research [44]. The main advantages of such methods include the low cost of research, the possibility to apply the questionnaire in the multimedia form, possibility of direct control over the data obtained, speed of research implementation, access to numerous respondents around the world; and the possibility for respondents to remain anonymous [45].
The sample was selected using quota sampling by the international agency Kantar Millward Brown, as the partner responsible for data gathering. The inclusion/exclusion criteria were applied. The questionnaire was addressed only to adults who met the recruitment criterion, i.e., declared to purchase food products of retail chains under their PLs. The question was asked: Do you purchase food products of retail chains under private labels? Respondents who answered "no" were excluded from the survey.
The sample was representative in terms of gender, age, and region of residence of the British and Polish population. This method of sampling procedure is known as non-probability sampling which includes quota sampling. We used statistical data on the population of Poland [46] and the UK [47]. The options for answers in the income question were based on statistical data and minimum salary in Poland for the year 2018 [48]. For UK consumers, the income was analyzed taking into account the National Minimum Wage in the year 2018 for persons over 18 years [47].

Statistical Analysis
The statistical analysis of the results were performed using Statistica software (version 13.3 PL; StatSoft Inc., StatSoft, Krakow, Poland). Statistical significances for nominal variables were determined using Pearson's chi-square test. For a more comprehensive and full presentation of consumer behavior in Poland and the UK, the Kohonen's neural network [68] and multi-dimensional cluster analysis was applied. Cluster analysis covers a wide variety of techniques for delineating natural groups or clusters in data sets It represents the process of organizing objects into groups whose members present similar features [69]. Additionally, we calculated the Cramer's correlation for each feature to indicate the strength of association between categorical variables. For all tests, p < 0.05 was considered significant.
The results of the exploratory analysis were confronted with Multidimensional Correspondence Analysis (MCA) algorithms which distinguished sociodemographic features typical of Polish and British consumers purchasing products available under PLs. This method presents the dominant features for the country and thus characterizes the population of the countries studied [70]. To present the correspondence graph of MCA, we applied gender, age, period of purchasing of PL products, education, income; and indicative share of PL products in total food purchases.

Sample Characteristics
The characteristics of respondents are presented in Table 2. The survey was attended by respondents, mainly from secondary or higher schools with varying financial status and from different places of residence, which results from quota sampling. Among Polish respondents, there were more females (52.2%) than males, most of them aged between 36-50 (26.6%) and 51-70 (32.2%). In total, 96.8% of respondents had secondary or higher education. As far as the place of residence is concerned, about 30% live in the countryside and 19% live in cities with more than 20,000 to 99,999 people. In terms of income, about 32.8% received a total monthly income of 2501 PLN-4000 PLN for 1 person in the household. Finally, 45.8% of respondents bought private label products of retail chains from1 to 5 years. By comparison, there were more men (50.8%) than women in the UK sample population, most of them aged 26-35 (31.2%), and 51-70 years (29.7%). The largest share in the structure of the surveyed population had respondents living in rural areas (23.8%), and in cities over 100,000 to 499,000 inhabitants. They have secondary education (56.2%), and the total monthly income was £1201-£1800 (26.0%). Most people bought PLs for over 10 years (46.2%).

The Period of Buying PLs
A comparison of answers to the question on the length of the purchasing period for PL products is shown in Table 3. The largest number of Polish consumers bought products available under PL within 1 to 5 years, followed by 5 to 10 years. Among British consumers, the largest group bought PL products for more than 10 years. The difference is noticeable among new buyers of PLs in the retail chains, i.e., up to 1 year (PL-9.6%, UK-18.8%).  Table 4 presents a comparison of the frequency of PLs' purchases from different food product groups by Polish and British consumers. In Poland, dairy products, cereals, non-alcoholic beverages were the most frequently purchased among food products available under private labels, while in the UK these were: bread, dairy products, fruit, and vegetables as well as frozen products. In both countries, consumers were the least likely to buy PL alcohol. In most cases, differences in the frequency of choice of PL products by retail chains in individual countries show a statistical significance (p < 0.05). The greatest differences were found for fresh products, i.e., fruit and vegetables, bread, meat and cold meat, and to a lesser extent frozen food, sweets, and biscuits. Cereals were the only product group that made Polish consumers more often choose PL products.

Main Factors of PL Purchase
The main factors influencing the PLs purchasing for the whole sample population and four consumer clusters are presented in Tables 5 and 6.
The consumers categorized into Cluster no. 1 were the ones who most agreed with factors influencing the choice of products available under PLs. The two factors with the highest average values in this cluster were: the ability to buy the same product repeatedly, and the availability of PL products. Lower prices compared to the leading market brands and feeling of safety and trust for PL products were also important for consumers. Cluster no. 1 is the most numerous, comprising 44.3% of the total population, including 48.2% of Polish consumers and 40.4% of British consumers. Cluster no. 2 includes 39.3% of the total population (40.2% from the UK and 39.6% from Poland). The consumers most agreed with the statement that the factor of choice of PL products was related to lower prices compared to the leading brands of manufacturers. More than 13% (13.2%) of people from the group of British consumers and 6.6% of Polish consumers qualified to Cluster no. 3. Among these consumers, the main factor determining the choice of PL products was the lower prices in comparison with products of product brands. An average value of about 3 indicating the neutrality of factors was obtained for the following items: wide product range and high product quality.

Opinions of PL Development
Tables 7 and 8 present opinions on the current development of the PL products for the whole sample population and four consumer clusters. Consumers in Cluster 1 are those who have the most positive opinions about the current development of products available under PLs. Three factors with the highest average values in this cluster were: better visual presentation of PL products, lower price of PL products while maintaining quality, and general improvement of PL product quality. Cluster 1 is the most numerous, accounting for 37.4% of the total population, including 43.6% of Polish consumers and 31.2% of British consumers. Cluster 2 covers 22.9% of the total population (22.2% from the UK and 23.6% from Poland). Consumers most agreed with the statement that an important factor in the development of PL is the lower price of PL products while maintaining their quality. Nearly 30% (29.8%) of people from the group of British consumers and 13.4% of Polish consumers qualified for Cluster 3. For the British, it was the largest group of responses and among these consumers, the main factor determining the choice of PL products was the lower price of PL products while maintaining their quality. However, in this group, an average value of about 3 was obtained for all responses indicating the neutrality of all factors. In Cluster 4, all factors were very important in the evaluation of current PL development.

Purchase Behavior of PL Products-The Correspondence Analysis
The analysis correspondence using MCA algorithms is presented in Figure 1. Polish consumers purchasing PL brands can be described as people above 51 years (51-70 and above 71), with medium and high income (income 4 and income 5), with secondary or higher education and purchasing PLs of retail chains for over 1 year, including a large share of 5-10 years. An important element is also the share of PL products in total purchases. Polish respondents most often indicated a 25% share, i.e., every fourth product in the shopping basket is from a retailer's assortment. British consumers are mainly people with primary and vocational education, with low incomes (income 1 and income 2), purchasing PL products for a shorter time, but the share in the shopping basket is 50%. These are young people aged 26-35 years. or more/£3500 or more; Indicative share of PL products in total food purchases: 0%; 10%; 25%; 50%; 75%; 90%; 100%; Red lines: mark the zone where most associations are concentrated, they facilitate the identification of variants of various characteristics that tend to co-occurrence with the GB and separately those that tend to co-occurrence with Poland (PL).

Discussion
The purpose of our study was to analyze consumer behavior towards PL products in the UK and Poland. Special attention was given to the motives for purchasing products offered under PLs and consumers' opinions indicating the PL development towards sustainable PLs. We also analyzed the frequency of purchasing PLs by food categories, length of the period of purchasing products under PLs, and the socioeconomic features of the Polish and British consumers.
The choice of Poland and the UK in our research was related to the stage of development of PLs. This has manifested itself, among other things, in the determination of how long consumers have been buying products available under PLs. Polish consumers usually bought PLs for less than 5 years, and British consumers for more than 10 years. This is a large time difference, however, it should be remembered that the market presence and development of PLs in Western Europe falls within the 1970s and 1980s. Whereas in Poland, until 1989, retail trade functioned as part of a centrally planned economy. The political transformation to a market economy initiated changes in retail trade, which took place in the 1990s. The first retail chains appeared in the late 1990s, only in the following years were own brands introduced and the first discount outlets were established [56]. In the initial period, PLs in Poland were basic, highly processed products, in simple packaging, and the main feature was low price while maintaining basic quality. In the UK, the transition from this type of PL assortment, called the first generation of the PL, took place much earlier [23]. The development of PLs in terms of the product offer, increasing the quality of products and increasing consumer awareness of PLs allowed for introducing premium products with their own product image, designed and created especially for a given retail chain [8]. The current stage of development of PLs is defined as the 4th generation, relating to the introduction of innovative premium products that further distinguished the main retailer brands and gain new customer segments [71]. Further development of private labels towards sustainable PLs is observed [7].
As an important element describing the consumer behavior of Polish and British towards PLs, we considered the frequency of purchasing particular categories of products under the PLs. Our research has shown that the most frequently purchased categories of PLs in Poland were dairy products, cereals as well as non-alcoholic beverages and water. Similar results were indicated by earlier studies conducted among the inhabitants of the Tri-City (northern part of Poland), in which dairy and cereal products were considered to be the most frequently chosen products of PLs [53]. However, as our research has shown, British consumers were most likely to choose fruit and vegetables, dairy products, bread, and meat and cold meat. The results obtained by us reflect the value shares of product categories available under PLs. In Western European countries, the highest value shares were observed for frozen food (43%), chilled and fresh products (39%), as well as non-alcoholic beverages (18.3%). However, these shares vary depending on the country, for example, the market share for frozen food ranged from 56.4% in Spain to 47.0% in the UK, 43.7% France, and 43.5% in Germany to 27.8% in Italy, and 24.4% in the Netherlands. In contrast, the share of chilled and fresh food ranged from 55.4% in the UK to 42.1% in Spain and 40.1% in the Netherlands to 21.8% in Italy. The share of non-alcoholic beverages ranged from 10.2% in Italy and 16.7% in Germany to 20.3% in the Netherlands and 21.4% in Spain [72]. In the US, the highest sales share in 2019 were recorded for bakery (36.6%), dairy (33.1%), and deli (23.6%), while the lowest by seafood (5.2%) and fresh foods (11.2%) [73]. On the other hand, in Slovakia, regardless of age, education, or income, the most frequently chosen categories of food were dairy products (approx. 40) and durable goods (approx. 35%). Lower results were noted for alcoholic beverages (approx. 30%) or frozen drinks (25%). For people with the lowest income, these were dairy products (46.6%), and in the richest group-durable goods like pasta or cans (39%) [74].
An important area of consumer behavior with regards to PLs was the identification of factors determining the purchase of PL products. Among the important purchase factors, the most significant were lower prices compared to the producer brands. At the same time, the importance of low prices of PL products in comparison to the prices of products available under manufacturers' brands was more important for Polish consumers than for British consumers. This indicates that in Poland the development of PLs is at an early stage, while in the UK the development of PLs is heading towards sustainable PLs.
Comparing our results with the results of other studies, two aspects should be pointed out. Firstly, the main reason for purchasing PLs is usually an attractive, lower price [18,25,29,72,75]. This indicates an earlier stage of development of private labels [17]. Secondly, the difference between PL products and producer brands is important. According to the 2018 IRI report, the average price of PL products in Europe in the year 2017 was about 70% of the average price of producer brands. The highest rate (83.7%) was observed in Italy and the lowest in France, where it was 61.3%. In the UK it was 78.1%, but compared to 2016 it decreased by 1.3% [75]. By creating a relatively lower perception of prices, retailers tried to have a positive impact on consumer loyalty to the PLs [76].
To indicate the PL development towards sustainable PLs, price as a factor for purchasing PLs should be assessed together with consumers' perception of the quality of these products. Our research has shown that the high quality of products available under PLs is a more important choice factor for UK consumers compared to Polish consumers. This aspect should be considered in the context of the stage of retail development, its concentration, and the market share of PLs. This determines the stages of development of PLs from the lowest price and lowest quality products to premium products [8] and sustainable PLs [7]. At the current stage of retail trade development, improving PL quality would help retailers to increase the number of customers, including those who focus mainly on quality [57] and sustainability [7]. This indicates that in the UK the development of PLs is at a higher level, which means that it is closer to sustainable PLs. This is confirmed by IPLC research on premium vs. standard offers in the largest retail chains in the UK. For example, Sainsbury's value-added PLs represents 16.5% of SKUs (stock holding units), in Asda-29.5%, and Tesco-19.8%. Such an offer includes, among others, premium, organic, free from, and eco-friendly products [62].
An important aspect of the development towards sustainable PLs is to compare the quality of products available under PLs with those of producers. Research indicates that the quality of PLs can be compared with national brands which make it equal and very competitive, but requires retailers to maintain high quality at an attractive price to encourage consumers to buy [77]. The Tesco Finest! (premium-priced foods from Tesco-large grocery retailer from the U.K.) is a good example of a PL with a positive image in the higher segment and a range of higher quality products [4]. This is confirmed by the fact that consumers' perception of higher quality will increase their willingness to purchase PLs [55]. Similarly, in Greece and Scotland, product quality is more important to consumers than price or packaging as a criterion for purchasing PLs [56]. At the same time, the appropriate price/quality ratio is indicated [55]. This is also confirmed by Polish studies, combining a good price/quality ratio with a wide range of PLs, availability of given products in each store of a given retail chain, or trust in retailer brands [36,49,78,79]. This aspect of the price/quality ratio also indicates the share of premium products. The Nielsen Company's research shows that the share of premium private PLs in the US accounts for 7.2% dollar share, compared to 5.9% in 2016 [80].
Currently, the concept of quality for the development of PLs towards sustainable PLs is being analyzed in two aspects. First, in the context of quality assurance systems for the production process and the final product, and secondly, in relation to the quality perceived of products, producer brands, and PLs by consumers. In response to changing consumer expectations of retailer products, it was necessary to develop an appropriate image of PLs so that the consumer could feel confident about the quality of the food product and guarantee health safety based on appropriate food quality systems, such as ISO 9001, BRC or other certificates in a given country [81]. Quality is perceived by the consumer as the superiority of the product or brand over alternatives and the overall assessment of the brand by the consumer [82]. Moreover, consumers consider the price, packaging design, composition, and food producer in particular to be product quality [83]. In this aspect, the perception of product quality of PLs is influenced by the taste, packaging, general appearance, and variety of choice [84]. All these features affect the consumer's perception of the product in a given place and time [85]. Product quality is often a subjective assessment and purchasing decisions are quick and spontaneous [86]. The perceived quality as an element of brand equity should also be considered, as the brand should provide consumers with a credible guarantee of quality [87]. In this aspect, perceived quality is described as the consumer's judgment of the overall excellence or superiority of the product [77,87,88].
Food safety and perceived food safety is also an important issue in the development of PLs towards sustainable PLs. Low prices and simple packaging, observed in the first phase of PL development, made the products available under PLs highly risky. Moreover, the lack of trust, lower product knowledge, and doubtful quality have led consumers to perceived PL products as high risk in terms of food safety [89]. The design of PLs in subsequent stages required attention to production safety aspects. At the same time, the retail chains responsible to the consumer for the safety of PL products require the implementation of the contracted production processes of PL products in accordance with the relevant safety standards [90]. In turn, the growing health and nutritional awareness of consumers are reflected in perceived food safety, described as the degree to which customers feel that the consumption of the branded products is harmless to human health [91].
Our study has some limitations. The analysis focused on qualitative data in relation to the PLs of food products. This research did not address the other product categories available under PLs. Future directions of research should refer to consumers' opinions on the quality of private label products in terms of the importance of price and other choice factors. It would also be important to compare private labels and producer brands in terms of choice motives, consumer preferences, and opinions. The analysis of determinants of perceived quality of PLs as an element of PL equity should be indicated as a very important future research direction. This is due to the growing share of private labels in the consumer purchasing structure and their development towards sustainable PLs.

Conclusions
Our research has shown that the consumer behavior of Polish and British consumers differs in terms of factors determining the choice of products available under PLs and opinions of PL development.
This is due to the stage of PL development towards sustainable PLs, as well as the length of time that PLs have been present on the market. PLs have been present in the English market since the 1970s, while its presence has been registered in Poland since the late 1990s.
The results of our survey are crucial for retail companies and international chains to identify the conditions for the PL development towards sustainable PLs on the one hand, and on the other hand, to identify tools that can become a sustainable-based competitive advantage on the dynamically changing retail market.