Correlation between market segmentation, industrial product features and context in design assessment

When referring to product design assessment, even with a standard evaluation format, the perspective from which the criteria are approached differs strongly from one market category to another, this having a direct impact on the accuracy of the method. In order to achieve an objective assessment, the product must relate to a frame of reference in accordance with the product’s destination, taking into account the user specifications and the actual experience of use. This paper represents the study of correlations between the market segment, product features and context and their degree of interdependence. Thus, analysing the relations between sections, the representative influence formulas for each considered feature were deduced, highlighting the extent to which the user’s typology and context relate to the product features.


Introduction
When addressing design assessment one of the major concerns is the extent to which the assessment can be considered objective. There is the question if the assessment can be approached from an unbiased perspective or is it possible that the method could be quantified and related to a proposed standard assessment system so that the results are as relevant as possible.
Based on a study of the subjectivity of design history Lees-Maffei and Fallan [1] identified the personal influence as a significant factor in design. The debates are even greater when the strong association between design and aesthetics is made. Atalay [2], studying Kant's approach to the theory of aesthetics, addressed the concept of subjectivity and demonstrated at the same time the existence of a component of universal validity. Considering the interpersonal validity, Travanini [3] also talks about a shared criteria of correctness, component of analysis similar to Cheng [4] which recommends criteriamarking scheme in order to make the transition from subjectivity to objectivity in design assessment.
The doubt of subjectivity cannot be completely removed but it can be controlled, as Ulrich and Eppinger [5] state that design is subjective but at the same time, you can determine qualitatively if the design has achieved its objectives. Thus, it remains the obligation of the assessor to fully research the entire context of the product and analyse based on criteria that relate to generally valid standards. A systematic approach that provides quantitative results can be achieved, but the relevance of the results depends on the insight on the correlation between the product and the purpose for which it was designed, the objectivity of the assessment being influenced by the in-depth knowledge of the consumer's profile and the extent to which it is taken into account, since the degree of objectivity can be increased by establishing a more precise structure as a frame of reference. The consumer behaviour has often played a central role in marketing, the consumer being seen as decision maker [6] for which strategies have been developed to ensure that the product is designed to meet its requirements as its influence determines the marketing strategies [7] [8], although there is also the possibility in which marketing ends up influencing the buyer behaviour [9].
In regards to the consumer and its correlation with the purchase decision, Lancaster [10] finds that the features of the product that influence utility are taken into account and not the product in fact. In this case, what can determine a certain feature and what it relates to, as the buyer may not be the actual user of the product and the role of the customer being different from that of the consumer [11]. For example, in the case of a toy intended for infants, the sizing of the product has to take into account the sizing restriction of the user, but in terms of colour scheme, although it must be appropriate for the user, it also influences the buyer (in most cases the parent, or an adult in question) and in the end, affects the purchase decision. Market segmentation can be somehow conditioned by the customer, however, it is the role of the designer to take into account the distinction between the two and to include as much as possible features that satisfy both categories, starting from the user especially if it is the case when a certain feature of the product may affect safety.

Sections of analysis -market segment, product features and context
The present paper is meant to study the relations between the user and the product, how product features can be influenced and also the way in which one feature can influence the other and how all this correlates, as the assessment must relate to product typology in accordance with its purpose, being considered all relevant parameters involved in the final design of the product.

Market segmentation
In order to best meet consumer requirements, market segmentation is used to facilitate the development of customized products for a particular category of consumers. The most common market segmentation categories are demographic such as age or gender, geographic with direct reference to location, psychographic which involves personality traits and what derives from it and behavioural segmentation based on purchase behaviour such as usage rate [12] [13] [14]. As pointed out by Dolnicar et al. [14], there is no ideal market segment but the most suitable for the given situation, although as proven before certain demographic variable are more significant than others [15]. Thus in the present paper, it was considered the market segmentation with the highest correlation with the product features. Were selected the segment criteria that can be applicable on an extended range of product types and having major impact, demographic such as age, gender, educational level, income and also culture, as a form of geographical and psychographic segmentation related to location with implications in product symbolism.
The product assessment determines whether the product itself is suitable, however, reporting to a proposed market segment is not just a simple reference of the product to one criterion since the segment criteria are also correlated and can influence each other. For instance, the buying habit differs depending on the income level [16], income being a complex variable in market segmentation and it relates also with education [17] [18] and with the consumer's location, as developed countries also imply a better standard of living and wealth. Income is also linked to a number of inequalities, such as that in relation to age [19] or the controversial gender pay gap [20]. The relation between gender and education [21] or gender and income highlights the difference between consumer and buyer, although women's incomes are overall lower, they are most often the decision makers when it comes to purchases [22] and it gets even more intricate when it comes to gender in relation to product features. As products with masculine traits are supported to the detriment of feminine ones, men are rejecting the idea of feminine products while women tend to accept products with masculine details [23]. An alternative to the ambiguity of gender traits could be set by the designer itself who would have the power to reduce stereotypes by creating genderless design [24], all the more so as the perception of gender related details tend to become an ever-changing factor.

Product features
Product features are elements of design and represent the characteristics that define the product, also referred to as products' physical properties [25], aesthetic attributes [26] or even principles of product semantics [27] and generally include colour, line, shape, form, weight, texture etc. as descriptive elements that, altogether, define the product. As a frame of reference in this study, the products' features have been narrowed to four major categories that integrate all relevant characteristics into a compact structure as colour (hue, brightness, saturation etc.), shape (line, contour, form etc.), material (texture, surface etc.) and dimension (size, weight, volume etc.).
The correlations between features are complex, although sometimes obvious when they influence each other directly such as the material in its natural form is already defined by a chromatic scheme or if the weight of the material changes implicitly the weight of the product will change, or the case of shape limitation for material because of geometry restrictions. As it can be seen in Table 1, some correlations are more difficult to detect, especially the perceptual ones in which the way a feature is perceived changes depending on the influence of another one, for example, changing a parameter such as shape can influence the perception on product dimension [28] [29].
In the table below are analysed the four proposed features and the type of influence relations between them, that can be both physical and direct or perceptual and indirect and each of these may have a different degree of impact on their relation of interdependence. The degree of illumination of threedimensional shapes influence the perception of colour.
perceptual ← Colour Shape Kingdom F A A, Wong K, Yoonessi A et al. [31] Colour contrast has an impact on the perceived shape and texture. perceptual →

Frayman B J and Dawson W E [28]
The shape of an object and the way it is presented influence the perception of apparent volume. perceptual → Shape Dimension Sevilla G and Kahn B E [29] The complete or incomplete shape of a product has an influence on the perception of sizing. Hodgson S N B and Harper J F [32] The materials may have constraints related to size, shape or geometry. physical The material used for lightweight design must take into account the constrains related to stiffness and strength. Colour saturation influences the product size perception.
Weaver P M and Ashby M [40] The material and the shape are connected as the shape in which a material can be formed is limited by the material itself. physical ← Shape Material Hodgson S N B and Harper J F [32] Materials may have constraints related to size, shape or geometry. Vangorp P, Laurijssen J and Dutre P [41] The material can be affected by the perception of shape or illumination.
perceptual → As it can be seen in Table 1, it is relevant not only the type but the direction of influence. Therefore, as presented in Figure 1, all the features are related more or less with each other and even the direction may differ. For example, the relation between material and dimension, as seen before, they are correlated but changing the product's dimension it won't change its material, it is a physical influence in one direction, material to dimension [32] [33], however, there is as well a perceptual influence because the material can be defined by a certain colour and implicitly hue, or shine and glossiness etc. and its perception has an influence on product dimension [34]. Considering the relations between product features, there are connections that although do not have a component of influence, there is to be considered the possibility of perceptual interdependence, for example, certain shapes are correlated with different meanings for the materials [42], affective association with a colour differs when it is perceived on different materials [43] and also, there are several recent studies [44] [45] [46] that while contradict Kandinsky [47] in shape-colour associations, they have some common points. In this case it is not highlighted on how changing the shape parameters can influence the perception of colour or vice versa, however, there are preference associations with a higher degree of occurrence, for example the association between circular shapes and the colours red or yellow.
Whether it is a simple link of preference or they even have a direct impact on the product itself, it is important to understand the correlations between features, as they play a major role in product design and the assessment phase and improvement of the product. The assessment highlights which feature needs improvement but if either one in question is modified, the change itself may affect another feature and eventually the entire product, being necessary to acknowledge the relations between them in order to obtain the desired product.

Product and context of use
Design, furthermore than relating a product to a specific consumer profile considering technical or ergonomic restrictions, it exceeds them and incorporates aesthetic and symbolism elements, therefore the culture through its implications becomes an integral part of the product details and their significance. The cultural meaning of goods [48] is reflected both by symbolism in the relation to the consumer tradition as a part of the market segment and also in the cultural context of the product that involves a historical analysis and past references [49] that provide insights in the way it and its features evolved over time, understanding the specific trends and as well as the evolution of attributes through brand identity and differentiation [50].
The context and the extent to which it is attractive also has the power to change the perception of product quality [51] and ensure the effect on the purchase decision. Above that, in the development stage, the product usability [52] must be fully understood and the product, through its attributes, must take into account the circumstances of use. In addition, there is the situation in which it is evaluated the way the product integrates in the environment and by technotope analysis it is studied the relation of coexistence between the product and the environment [53]. Thus, in this paper, as presented in Figure  2, the context was proposed as a third category of relational analysis and includes a historical branch with the product's cultural implications and its evolution in time and a secondary one with reference to the environment and how the product is correlated to its context of use.

Study of correlations between sections
The elements of each proposed section were presented in Figure 2, alongside with the specific correspondent, section A for the user (market segment), B for the product features (these having a central role in the relation between the other two sections) and section C for context. In the previous chapter it was established how the elements impact each other within the same section. In order to determine how the product features are related to the market segment or context and to establish the existing connections, in Table 2 are presented previous studies that analyse the relations between sections. The correlations are intricate and the absence of a mention does not represent the absence of the corresponding connection, they just are not part of the prior research in question, as the studies do not contradict but approach the subject from different perspectives. The shape has meaning associations in relation to femininity and masculinity. A2 B2 Jadva V, Hines M and Golombok S [57] There are associations between the child's gender and product colour or shape preferences. In the selection of the material (through its shape, meaning and other properties) both the typology of the user and the context of use must be considered. Through cultural nostalgia, the designer has the opportunity to use product attributes traced in the past in order to evoke familiarity.

A5 C1
Wastiels L and Wouters I [75] In the selection of the material in architecture, are relevant both the material's physical properties and the processes involved as well as the meaning of the cultural and use context.

Ulmeanu M E and Crăciun A E [53]
Colour is a relevant factor in the harmonious relation between the product and its context of use. B1 C2 Brooker G and Stone S [76] The elements of form and structure of the interior space are associated in relation with the history and context of the environment.

B2 C1, C2
Tseng Y S and Ho M C [77] Integrating product elements that invoke the past is a design strategy meant to generate emotional response from the consumer.

B1, B2, B3 C1
The relations between the sections were structured and displayed in the proposed correlation matrix (Figure 3), in which was presented the graphic and numerical notation of the sections' relations. The connections were noted according to the degree of interdependence, where a relation of rank 3 is considered of high impact, rank 2 of medium impact and rank 1 for minimum impact, being also the possibility of no correlation. The missing link is between age and gender, although there is a well-known gender difference in life expectancy, it cannot be determined a direct connection between gender and age relevant to the proposed subject. When analysing the matrix, it can be seen that although two elements are defined by the maximum correlation, each in turn can be strongly influenced by another element, for instance, the connection between the product dimension and user age, as the age also has a rank 3 link to the context of use, both through the environment that is specific to it and through the temporal affinity influences that can be found in the product details, since it is a strong connection between the user age and historical frame.

Product features in relation to the market segment and context
In order to deduce the implications and the way the product features are influenced, following the interpretation of the matrix (Figure 3) and the influence relation between features (Figure 1), the representative formulas for each feature were concluded as follow, equation (1) for colour, equation (2) for shape, equation (3) for material and equation (4) for dimension, as the corresponding indices are presented in Figure 2.
For each feature, the first relation represents its relation to the market segment and context, meaning the elements on which it is conditioned in its analysis, and the second one represents the correlation of influence within the same section and how it can affect another feature or can be affected in turn. In which case, it was noted with minus if it has influence on another feature (implicitly the other feature is influenced by it), with plus if it is influenced by another feature or plus and minus if it is bidirectional in the relation of influence.

Colour
The colour is primarily correlated with gender-specific associations [ [68], not necessarily as a restriction as there are chromatic preferences depending on the age segment. Additionally, colour it is related with the educational level [60][67] [68] and history [77] as some shades are specific for certain historical periods, for instance, as art-deco is associated with golden metallic details. Although with less importance, the income [67] [68] is also related to colour with associations regarding socio-economic status.
In its relation with the other features, the colour can be generated directly by the natural shade of the material [35] [36][37], association that can be excluded if artificial dyes are used to cover the surfaces. In terms of connection with shape, the colour may influence [31] or be influenced by it [30] as it may affect also the perception on size [38] [39], for instance, the light-coloured details seem larger and the dark ones seem smaller by comparison.

Shape
The shape of the product is firstly related to gender [56] [40] and it can as well affect the perception of it and its reflectance [41]. Furthermore, the perception on shape can be influenced by colour [31] and it can influence it [30] as well as the dimension [ [69] is linked to material, there are specific associations, as is the case with metallic products that are considered masculine.
In relation to the other features, as mentioned, material can define the colour of the product [35] [36][37], may physically limit the form [32][40] and be perceptually influenced by it [41], however in its relation to dimension [32][33] [34], the material determines the entire weight of the product, which has a direct impact, but does not directly affect its size.

Dimension
The product dimension has an important relation with age [ Thus, when approaching an industrial product from the perspective of design assessment, for each attribute, it is recommended to consider it depending on the product typology, taking into account, gradually, the degree of interdependence of its relation to the market segment and context.

Conclusions
Within the paper, the proposed sections and subordinated elements were studied in turn, the market segment (age, gender, education, income and culture), the product features (colour, shape, material and dimension) and the context (history and environment), being analysed both the relations within the same section and the general correlations between them. The results were centralized and presented in the matrix of correlations along with the degree of impact between elements, from which the corresponding formulas for attributes were deduced, being presented the way that a product feature is influenced. Thus, the purpose of this paper is to help designers, either in product development or in assessment both after and before the final production (in the concept phase) by approaching the features based on the hierarchy of influence elements within the market segment and the product's context of use, being established the extent and the direction in which a feature is affected. Improving the product by modifying a certain feature, the proposed study highlights also what other feature is affected or what can influence it in turn, in order to achieve the desired results.
The presented study is not an actual assessment method and does not approach the industrial products from the perspective of the importance of aesthetics, ergonomics, symbolism etc. [78] However, it takes those principles into account and represents a foundation in design, since the proposed matrix of correlations is set as a frame of reference of the product in relation to its purpose and the perspective of use. As Dumitrescu states, except for functionality, product attributes cannot be considered absolutely positive or negative [79], the design assessment must account for the purpose of the product and the values of the market segment [80].
In regard to the study limitations, were considered the sections elements with major impact in the interdependence relation, thus in order to increase complexity, the market segment can be approached from an elaborate perspective that includes more from the other market segmentation categories with implications in detail in lifestyle or purchase behaviour. Furthermore, although they were implicitly included in the product features, the subordinate features could be studied individually such as considering the texture separately and not as an integral part of the material, as may be the case for brightness or gloss and colour, or other relevant subordinate features.