CONSUMER BEHAVIOR MODELING OF “SMART” SCALES CHOOSING

Objectives: at the beginning considered approaches for analysis of consumer behavior, its evolution, basic principles, advantages; in relation to products and household goods of daily demand, and factors affecting behavior and choice; the goal of the study was to develop a model for consumer comparative assessment of products offered on the market based on a comparison of the basic user and technical characteristics of these products that are important to potential buyers. Methods/Approach: was developed buyer’s multicriteria model for the estimation and selection of household smart diagnostic scales using the methodology of fuzzy modelling; were given groups of users of household diagnostic scales for monitoring the state of the body on the Ukrainian market; consumer criteria when buyers choose smart scales had been identified, described and formalized; as a method of modeling, fuzzy logic was chosen, because this approach allows accurately reflect consumer preferences and potential choice. Results: applied model for estimating qualities of smart scales by customers in Matlab was developed; the membership functions and terms were defined and constructed, as well as fuzzy rules to make decisions on the estimation of compared smart scales; the numerical example for scales presented on the market was given. Conclusions: calculations and analyze of results confirmed the applicability of the proposed approach and its correctness for modeling consumer behavior by fuzzy logic models; the prospects of application, development, and improvement of the developed model and the proposed approach were determined.


INTRODUCTION
As is well known, the study of consumer behavior becomes a very important area of applied economic research in the context of globalization of markets for goods and services (Matyushenko et al., 2020;Ramazanov & Petrova, 2020).This fully applies to consumer goods to maintaining health, healthy lifestyle, self-monitoring of the human body and exercise physical culture.
Recently, a significant number of such fundamentally new products have appeared (Dubovik et al., 2017), in particular, various fitness devices, devices, and technologies based on the principles of a smart home and smart appliances for everyday use etc.
Traditional household goods, in particular, intended for health monitoring (scales, thermometers, toothbrushes, blood pressure measuring devices, glucometers, hearing aids) are also being improved.They acquire qualitatively new consumer properties associated with advanced computer technologies, the concept of smart home appliances, according to smart home technologies and Internet of things as a general direction for the development of technical goods for daily use.On the other hand, the rapid development and dominance of the mentioned Internet technologies and the corresponding approaches of social media marketing have made the consumer choice of such goods more conscious, motivated, information and mentally justified (Richard and Chebat, 2016;Richard and Habibi, 2016;Vatamanescu et al., 2017).At the same time, the choice of a certain product by the buyer often continues to be largely emotional, subjective and personal action (Scheibehenne et al., 2015;Stuart et al., 1987;Villiers, 2015).
Therefore, in this case, the issue of modeling consumer choice becomes quite relevant.It should be noted that the basic fundamentals of it remain various forms of expert surveys of consumers, their processing by various economic and statistical methods (Anghelache et al., 2016;Bushra, 2015;Ertz et al., 2016;Hakkak et al., 2015).However, often such approaches are faced with quantitative deficiency, qualitative ambiguity, the fuzziness of the initial information, which complicates their further application and reduces the reliability of the resulting calculations (Kavita and Shivani, 2016;Oliveira et al., 2015;Rybanská, 2015;Sakkthivel, 2012).
One possible approach to overcome these difficulties is to apply fuzzy sets theory and fuzzy modeling to formalize consumer choice (or product evaluation).The availability of specialized computer programs makes such models simple enough for development, testing, convenient for subsequent practical application (Dorokhov et al., 2010).More detailed information about usage of fuzzy modeling for economics in general can be found in other similar studies (Ferrer et al., 2020;Imanov, 2021).
As an example of the practical implementation of this approach, in this paper, we propose a model of multicriteria evaluation (and possible consumer choice) of intelligent household electronic diagnostic scales, from the number of household appliances offered in the Ukrainian market for health.

Basic paradigms in the general analysis of consumer behavior.
Analysis of the literature on the study of consumer behavior shows the presence of two main points of view: the traditional view of the motivation and behavior of the buyer (traditionally positivistic paradigm) and the interdisciplinary marketing approach (interpretive paradigm) (Markovic et al., 2021;Christofi, et al., 2023;Kastanakis et al., 2022).The positivistic approach assumes an objective view of the world and uses quantitative methods of investigation.The paradigm of interpretation is subjective and often uses qualitative methods.
Traditional researchers seek to decipher the causes (generating certain components of consumer behavior) and postulate relevant generalizations.Supporters of the interpretive paradigm tend to treat each consumer individually and consider each act of consumption to be unique (Alharahsheh and Pius, 2020;Ma and Ma, 2022;Oleksy-Gebczyk, 2023).
The positivist-traditionalist paradigm for several decades (approximately, 1900-1970) had a significant impact on economic science (Thielemann, 2020;Rabby et al., 2021;Jaja et al., 2022).Its main assumption is that human thinking is the driving force of all human actions.Also, positivists postulate the existence of the supreme truth, which is unique, objective, and can be revealed only through science (Rahi, 2017;Lim, 2023).
Positivists perceive the world as a rationally organized space, with a clearly delineated past, present and future.The traditionally positivistic paradigm has evolved from pure traditionalism (in which three main points dominate: rationalistic view, behavioral and cognitive standpoints) to neopositivizm (Table 1).
The latter complements the values of the conservative paradigm by developing mathematical models and recognizing society as an important determinant of consumer decisions and behavior (McCloskey and Silvestri, 2021;Grace, 2021).A rationalist paradigm suggests that consumer behavior belongs to the unique reactions that they possess.
The main assumptions of this paradigm are the following: people have a full understanding of their needs and know all the available means for their satisfaction.Consumers distribute and spend their resources (revenues) in order to meet those needs that are more useful to them and give more pleasure (Schifman et al., 2010).
So, people buy goods (services), the costs of which can afford.The purchase decision is equivalent to allocating resources to maximize utility within financial constraints.The consumer evaluates each alternative and acts rationally (utility maximization is the only motive of behavior).That is, the rational paradigm is based on the classical theory of the marginal economy, according to which price has primary importance when all other variables remain on the same level.Human needs, attitudes, and motives can be measured by analyzing the distribution of resources, income and budget constraints of consumers (Balaure, 2003).Such economic models support behavioral hypotheses (the higher incomes -the higher costs).However, their effectiveness depends on whether all individuals act as computers in making their decisions (Pachauri, 2002).
Although the relationship between income and expenditure is not meaningless, consumer behavior is much more complex (Persky, 1995).At the same time, consumers often do not have enough information, motivation or time to make ideal rational decisions without taken into account the daily diverse social and cultural influences during each day of their life (Simon, 1997).It will be simplistic to assume that the determining factor is the desire to optimize only the monetary component of the solution.Despite this, such models (Muth, 1966) served as starting points for the further development of consumer behavior theories.
If the rational paradigm emphasizes the importance of costs and resources (as the main factors of consumer decisions), then the behavioral paradigm (learning model) emphasizes the role of external and uncontrolled factors (dependent, however, on individual learning processes and previous consumer decisions).The basic premise is that behavior is determined by the actions of people under the influence of certain stimuli.The consumer acts as a black box that reacts to external factors encountered (Peter and Nord, 1982).Therefore, the behavioral paradigm tries to define a complete set of external sources that determine the actions of consumers in a certain manner.The main approaches are classical and operant conditioning (both are reduced to learning, but through different processes).In line with logical positivism, it is asserted that objective and empirical methods of exact sciences can be applied to the study of consumer behavior (Eysenck, 2000).
Classical conditioning assumes that the mentality of the individual is a "black box" between inputs and outputs.And if the inputs can be monitored and monitored, the outputs can only be analyzed as the consequences of input data.However, the assumption that occurs inside the "black box" as a result of a certain input, is only a posteriori conclusion to which one should be treated with caution.
The learning process itself includes incentives, suggestions, reactions (Kotler et al., 2002).Incentives are personal motives that determine the need for certain purchases.Proposals are the result of the interaction of external factors and the response of individuals to stimuli.The interaction of incentives and proposals triggers a consumer reaction.According to the theory of classical conditioning, different consumers will have similar reactions when they encounter the same external stimuli.
The generalization of stimuli and individual responses to all consumers (the so-called classical behaviorism) is an attempt to define a complete set of external factors affecting consumer behavior without taking into account that individual mentality or internal states do exist (Bray, 2008).This generalization of behavior ignores the role of the individual's personal experience in interpreting external stimuli.
Radical (operant) conditioning recognizes the existence of personal experience and feelings but considers them secondary (Nye, 1979).The consumer reacts only to incentives that give personal benefits and avoids situations that may prove harmful.This behavior is formed in the process of long training.The corresponding theory of prospects explores the irrationality of consumer behavior and the influence of various factors on the adoption of consumer decisions.Such studies develop a common knowledge of human behavior.The diverse range of views and explanations associated with sustainable consumer behavior makes it a complex phenomenon to understand and predict (Ismailov & Krivins, 2023).
But behaviorism can only partially explain the complexity of human behavior and decisions (Stewart, 1994).After all, behaviorism does not reflect the relationship between external exits and internal psychological processes, as well as the conclusions that consumers make in the process of acquisition.However, advertising and other promotion methods successfully use the principles of behaviorism (Lai and Ya-Shin, 2011;Scheibehenne et al., 2015).In contrast to the behavioral theory, the cognitive paradigm (information processing theory) emphasizes the central role of information components in the processes of making consumer decisions.
Consumers are seen as solvers of problems that actively use available information to control the external environment.The current culture of consumption must change to enable a transition to a circular economy; otherwise, policies at EU level, such as the European Green Deal and the Circular Economy Action Plan will remain only theoretical instruments that will not change the course of the current unsustainable economic paradigm.(Ismailov, 2023).Studies (Allen and Madden, 1985;Langer, 1983) prove the existence of unconscious cognitive processes, the actions of which lead to rational purchasing decisions (Solomon et al., 2010).
The cognitive paradigm improves understanding of consumer decisions, their successive actions, feelings, and behavior (Marsden and Littler, 1998).The cognitive paradigm recognizes that internal factors and processes (cognition, feelings) can lead to action in the absence of external stimuli.From an empirical point of view, cognitive theory emphasizes internal processes.However, it analyzes consumers as identical, congruent and symmetric entities that process the inside information in the same way.Numerous cognitive models try to present reality and predict the generalized behavior of consumers.Researchers point out that positivism pays much attention to material well-being, that its ideology generalizes the cultural homogeneity of predominantly Western societies (Solomon, 2004).Critics argue that focusing on science and technology positiviztically denies the social complexity of the world in which consumers operate.
Interpretation paradigm (emerged in the late 1980s in tandem with the development of critical thinking in marketing (Kassarjian, 1982)) emphasizes the importance of subjective experiences, symbols and cognitive abilities of consumers.They enhance their own possibilities for interpreting realities based on cultural and perceptual experiences.This paradigm (unlike the traditionalist point of view) better reflects the interests of consumers, their role in understanding reality, in forming a set of expectations that lead to the formation of individual consumption experience (Calder and Tybout, 1987;Hirschman, 1993;O'Shaughnessy and Holbrook, 1988).
If the positivistic paradigm is aimed at predicting behavior on the basis of direct observation, then the interpreter seeks to understand this behavior.Traditionalists postulate the identity of specific causes of consumer behavior, whereas interpretive approaches analyze multiple events where people participate directly or indirectly, consciously or subconsciously.The paradigm of interpretation admits that there is often no separation between the researcher and his object of study.Thus, the researcher himself becomes part of the research that he conducts.A number of authors (for example, (Usunier and Lee, 2005)) admit differences in the level of understanding of the interpretational approach, even between European and American researchers (in particular, European attach great importance to cultural differences of consumers, their different personal experiences).Interpretive (postmodern) paradigm question (Firat et al., 1995) rationalistic models and methods of analyzing consumer behavior (mathematical modeling, quantitative and qualitative methods), the very idea that consumers can be understood and objectively studied.Some authors (Marshall, 2012;Morgan, 1992) emphasize the need to integrate traditional and postmodern approaches into an integrated system (paradigm).It provides that understanding consumer behavior can only be achieved through the adaptation and sharing of several paradigms and/or their parts (although serious complications in the comparability of paradigms are postulated in (Kuhn, 1962).
The basic principles of this approach are as follows: no part of the consumer experience can be understood if it is considered in isolation.The combination of the results obtained by different methodologies, theories, and mathematical approaches makes it possible to obtain better and reliable information about the behavior of consumers in comparison with the application of any particular approach.
A holistic approach uses methods that can identify consumption habits and their recurrences over time (O'Shaughnessy and Holbrook, 1988).Consumer behavior is understood as a continuous process of buying and consuming.Despite the advantages of a holistic approach, its complexity causes a lack of specific applications in the analysis of consumer behavior.However, the study of consumer behavior does require a holistic application of the principles and tools of various disciplines and applied fields of research (Engel et al.,1986).At the same time, it is the basis for more narrow research in marketing, strategy, financial planning, organizational behavior and applied economic analysis.The lack of deep and thorough knowledge of these relations has a direct impact on decision-making on tax planning, payment of taxes, social security contributions, etc. (Aleksandrova & Ismailov, 2021).On the one hand, the growing consumer needs led to an increase in industrial energy consumptionto produce goods and services, the economy needed more energy, and on the other handimproving the living standard of households led to an increase in households' energy consumption (Todorov, Aleksandrova, & Ismailov, 2023).In general, the analysis of consumer behavior creates the basis for the evolution of these areas of economic research using various research tools and disciplines The behavior of everyday goods consumers.
Obviously, consumers (buyers, customers) are valuable assets for any commercial organization in a competitive market environment.Therefore, to achieve success, it is very important to understand and predict their behavior.Consumers are individuals (groups) who choose, buy, use goods, products, services, ideas, experiences to meet needs and desires.In other words, consumers are the final destination of any products or services.Analysis of consumer behavior contains components of psychology, sociology, social anthropology, economics, and is directed to the processes of making decisions (individual and group).
At the same time, the characteristics of individual consumers (economic, social, demographic, behavioral, etc.) are studied; the influence of family, friends, reference groups, and society on them is assessed.The study of client's behavior is based on consumer behavior of the buyer.In this case, the client can be in the role of users, payers, buyers (Thapa, 2012).There is a strong relationship between consumer behavior and the marketing strategy of the company, as its success depends on the understanding of consumers' behavior managers.The decision of consumers about the purchase testifies to the extent to which the marketing strategy corresponds to market demand.So, marketing begins and ends with the consumer.
Studying the behavior of consumers allows you to determine the direction of its changes and determine the desired trends in product development, attributes, alternative methods of communication and the like.
However, consumer behavior is difficult to predict even for experts (Armstrong, 1991).
Consumer behavior should be considered the most important variable in marketing activities (which is difficult, but desirable to control).A product (service) should be considered not only in terms of physical characteristics but in the context of its own image (in accordance with the social, psychological conditions, views of the individual consumer or group) (Proctor and Stone, 1982).Then you can improve understanding and forecasting of both the subject of purchases, motives and frequency (Schifman and Kanuk, 2007).
An important underlying assumption (in studies of consumer behavior) is that people often buy goods for their subjectively palpable values, rather than essential basic functions (Stávková et al., 2008).Often, out of habit, consumers evaluate the product not only by its main attributes (the utilities that it provides).
They consider the product according to real, specific qualities in combination with some extended characteristics (less significant).The latter sometimes even prevail, creating imaginary advantages for the consumer (for example, appearance, service, advice and after-sales service, etc.) (Foret and Procházka, 2007).
Therefore, it is necessary to understand the main requirements of consumers and to study the main causes and characteristics of their behavior.That is determine who is the customer, what they want, how they use the product and react to it.Usually, customer needs are studied by conducting empirical studies (consumer surveys) to identify the components of consumer behavior (models, factors, and incentives).The behavior of visitors (when, why, how, they buy the product) can be represented by a black box model (Table 2).It shows how incentives, consumer characteristics, decision-making processes, consumer reactions are interrelated.These stimuli can be interpersonal or intrapersonal (Sandhusen, 2000).Such a model is connected with the theory of behaviorism, where the processes inside the consciousness of the consumer are important, and the relationship between its stimuli and reactions is important.At the same time, although marketing incentives are developed and created by producers and sellers, the effectiveness of their impact on the consumer depends significantly on social factors (based on the economic, political and cultural conditions of society).
Thus, the buyer's black box contains his perception, decision-making process, reaction, and actions.The buyer's personality affects the perception of irritants.The decision-making process determines how the behavior becomes.Important to understanding the behavior of the buyer are factors that determine its characteristics as a black box.These factors are classified and configured in various ways (Table 3).In general, these factors are divided into five groups: physical, personal, cultural, social and marketing mix.
They stand out to distinguish between the impact on behavior and to determine the target consumer segments.
As a result, market fragmentation and targeting of marketing activities into individual categories of consumers are carried out.After all, consumer desires are different for different types of behavior.At the same time, the more expensive the product, the more information the consumer needs and his involvement in the purchase process increases (Table 4).High involvement occurs if the product is very in demand or expensive (for example, the consumer is very actively involved in buying a car).On the contrary, low involvement is observed when the consumer is not very active in buying, in particular at low cost (for example, buying salt, the consumer is not too interested in buying).Also, differences in the buyer's perception of brands should be taken into account with significant or (on the contrary) small differences between them.
Therefore, from the point of view of participation in the actual purchase process, four basic types of consumer behavior are possible.Complicated behavior: when the consumer is very involved in the purchase and knows about the significant differences between the brands.Then the consumer requires a maximum of information about the characteristics of the product.The marketer needs to convincingly present the advantages that determine the positive components of the proposed brand.Behavior associated with diversity: there is low consumer involvement in the purchase of the product, while there are significant differences between brands.In this case (quite often) consumers buy different products not because of discontent, but in search of diversity.The marketer should be encouraged to buy exactly this product (discounts, bonuses, discounts, free samples, advertising, etc.).Dissonant behavior: the consumer is very involved in the purchase, but there are only minor differences between the brands, which can often spontaneously change the choice of the product.Behavior by established habit: there is low involvement and there is a slight difference between brands.The consumer simply buys the product to which he is accustomed for a certain previous period of time.

Target groups of users of household diagnostic scales for monitoring the state of the body.
As is well known, the target audience is all real and potential consumers of the goods, interested in it for a certain time or ready to change their preferences in favor of this product.The target audience includes both direct consumers and those who make purchasing decisions or affect it.It is consumers who determine the success of the product (its producers and sellers) on the market.
A comprehensive study of the target audience of medical products underlies the understanding and identification of key consumer needs.It gives the pharmacy the opportunity to meet these needs with the help of appropriate product offers, and therefore, be competitive in market conditions.Understanding the structure and characteristics of the target audience ensures the development of a successful marketing strategy.
The effectiveness of marketing communications (the development of channels, types, means of promoting pharmaceutical products) directly depends on the characteristics of consumer behavior of the target audience.
The main criteria for its analysis are: geographical (country, region, city, population density, climate) demographic (age, sex, family size and stage of its life cycle); socioeconomic (occupation, education, attitude to religion, nationality, level of income), psychographic (lifestyle, personality type, personality traits, life position) behavioral (motives of buying, sought-after benefits, type of buyer, perception of goods, organizations).
The methods of research of the target audience are numerous and varied.The most important are the primary, direct (field) methods of marketing research that receive marketing information directly from its source.Despite the laboriousness, cost, duration of processing information and its subjectivity, in practice, quantitative methods of the interview are most often used: questionnaires and interviews.They provide the complete information about the target audience.
We conducted marketing research to study the target audience and identify consumer preferences when buying diagnostic scales for home use.They were carried out using questionnaires with elements of interviews among visitors to medical equipment desk of Pharmacy №2 (20, Constitution Square, Kharkiv, Ukraine).We used the blind non-repeated sampling (with 590 respondents).Target audience structure by ages (full years old), occupations of respondents, and sources of information about household diagnostic scales are shown in Table 5.The main motive for weight control for 62% is beauty, beautiful appearance, for 38% -is health.In general, informal Internet and WOM (Word of Mouth) communications are extremely important in the promotion of these products.Personal sales and consultations of sellers also play an important role in obtaining information about household appliances for monitoring the state of the body.When developing a marketing strategy and planning a complex of marketing communications, the lifestyle of potential and real buyers becomes important.Potential buyers of household diagnostic scales are consumers who carefully monitor the health status, proper nutrition, physical activity, control the weight and other components of their body.
These are not only people with abnormal (superfluous or insufficient) weight (middle, older age), but also all for whom normalization and weight retention is an important health issue.Therefore, the target groups of potential users of the diagnostic scales are: people of normal weight (watching their bodies), people with excess or insufficient weight (other health problems), youth and adolescents; young mothers and pregnant women (those who plan pregnancy), elderly people; athletes (actively physically trained in medical, preventive, healthimproving purposes).
It is clear that the motivation to maintain a normal weight and control the body composition of these groups are different.However, various household diagnostic scales (offered on the market) can meet their requirements taking into account the characteristics of each of the listed consumer groups.
Pharmacies (when they offer these devices) should only develop an appropriate marketing strategy, plan effective marketing communications in accordance with the characteristics and behavioral characteristics of various groups of potential and real consumers.This is a necessary condition for increasing the competitiveness and successful operation of pharmacy institutions in market conditions.It should be noted that in spite of a certain number of scientific publications on the interaction of pharmacies and customers (visitors, customers), the overwhelming majority of them have focused on issues related to medicines and related medical products.
On the contrary, the marketing components of sales and promotion in the pharmacies of complex technical products of medical purpose, the functional of which provides control and maintenance of the health in the household conditions by the population (inhalers, glucometers, ionizers, diagnostic scales, air purifiers, quartz lamps, etc.) pores have not been adequately researched.

Characteristics for comparative evaluation and choice of diagnostic scales.
Health and physical aspects of human life are very important, and for their control are needed (and now become  They can measure and calculate (Table 6), show and memorize a number of important parameters of the state of the human body; a namely: total body weight, body fat (as a percentage), percentage of internal fat, amount of water, muscle mass, bone mass, basal metabolism level, physical development rating, caloric intake (daily and recommended), biological age (relative) and others.
Considering the process of choosing devices for measuring the weight of household use by customers, it is necessary to consider for what purposes they are bought by various categories of consumers.Of course, the best is a device with additional functions that will satisfy the needs of each member of the family (but not too difficult to use and care for).
Therefore, the important characteristics are the following components: memory, on and off, user definition, calculation of normal weight, determination of fat, muscles, water in the body.Among, other parameters can be called quality of the coating (stability, slipperiness), waterproof housing, leg adjustment, ease of movement, the size of the display (numbers) and its brightness.Convenient and functional are models with a wireless monitor, with the ability to exchange data with a personal computer or smartphone.
Consideration of the main parameters (characteristics) for comparison (consumer choice) of diagnostic scales, detailed study and generalization of various information (according to their different models), showed that all these characteristics can be broadly divided into three groups (Table 7).Thus, we will take into account the following main components that influence the consumer assessment: -the price of the device, we will consider the price segment 300 -3000 UAH (8 -75 EU); -the possibility of measurement and analysis, the number of measured and calculated parameters; -special advantages, manufacturer, brand, warranty, design, platform quality, etc.; -additional user-friendliness, memory, display, remote, communication with smart devices, software.

Devices offered in the market for diagnostic control of body weight.
On the Ukrainian market of health products (in particular, technically complex devices for home use, such as diagnostic scales), the basic offers are presented in the Internet shops of a wide profile, in shops and salons of medical equipment, in drugstores and pharmacies.
Among a large number of different models and brands, we selected for the further comparative consideration several models of scales of the average price category, which are available and offered for purchase by buyers.
For some of their parameters, the integral score consists of the sum of the scores for the presence of each individual element according to Table 8.The final price, technical, operational, service, and consumer characteristics of the scales chosen for consideration are summarized and given in Table 9.As a result of evaluating the devices, selected for consideration, for these individual components by summing the corresponding scores, you can get some integral evaluation of the qualities of specific diagnostic scales, taking into account additional user facilities and capabilities.This generalized ball score will be used (as a separate parameter) in the further construction of the model of consumers' assessment of diagnostic scales using the theory of fuzzy sets, in the specialized module FuzzyToolBox of MatLab software.
The model for the evaluation of diagnostic scales based on a fuzzy approach.
We propose to consider (as the initial data of the evaluation according to the methodology of the fuzzy-multiple approach) the three main linguistic characteristics of the devices proposed for consideration and comparison.
This avoids the excessive complexity of the computer model.After all, the methodology for creating, testing and debugging the model remains almost the same with increasing the number of input variables.But the volume of individual rules of decision-making increases significantly with a close final accuracy of the results.
Thus, the following parameters (variables) were chosen as the main: price (300 -3000 UAH), functions (1 -15 main measured or calculated parameters), characteristics (5 -20 points for aggregate evaluation of individual consumer characteristics, service capabilities, etc).Each of them can be represented by a set of three linguistic terms (price: small, medium, large, functions: limited, sufficient, exhaustive, characteristics: low, normal, high) with triangular or trapezoidal membership within specified intervals of numerical values.The resulting linguistic evaluation (score: weak, sufficient, excellent) can also be represented by triangular membership functions with the presentation of the final result of the evaluation of each individual model of the device in the range of 1-10 points.The corresponding numerical data for building the necessary input and output membership functions are given in Table 10.The corresponding model was constructed in MatLab Fuzzy Logic Toolbox.It is understood that the proposed and reduced in the table concrete boundaries of various linguistic estimates of parameters are somewhat arbitrary (in this particular case, determined from the expert point of view).But after creating the model in the process of testing and verifying it, it can be easily changed (without destroying the model as a whole), as well as adding the necessary terms and evaluation rules for individual parameters.For all the terms of each of the three input and output variables in the program (according to the data in Table 10), corresponding membership functions are constructed, the graphical appearance of which is shown in Figure 1.Next, needed to define and enter into the computer model all the rules of decision-making (integrated evaluation of the device with three available input parameters).
In this case, a complete search of all possible variants (combinations) of the input linguistic terms contains 27 rules (three input variables with three terms in each).It is clear that with an increase in the number of variables (input evaluation parameters) and (or) terms in them, a complete search will lead to increase in the number of rules.
An example of the interaction of rules for fuzzy inference is shown in Figure 2. The values of the input parameters are as follows: Price is 1750 UAH, Functions is 12 points (functions), Characteristics is 16 points;  .Additional possibilities for model analysis (its verification, adjustment, adjustment) provide visualization of so-called fuzzy logic output surfaces (Figure 3).And vice versa, determine the parts of values of input parameters, where their change practically does not affect the value of the result.That is, you can determine which one and how much improvement (of one or the other) the characteristics of the device will decisively affect its overall assessment (its increase) by consumers (customers).
Concluding the description of the model, we note that it is possible to generate the corresponding program code.It can be used (built-in) into other programs (like their fragment).So the proposed model can be used for multi-stage calculations, where the described approach (to multicriteria estimation) is only part of more complex calculations.

DISCUSSION
The developed and presented a model for the evaluation of diagnostic scales was used to obtain a generalized estimate of several of their models.The results of the calculations are shown in Table 11.The obtained calculated results show that the final score in points for the best model reaches only five points.Although the maximum attainable score is ten points.This can be explained, in particular, by the following reasons: overestimated prices dramatically reduce the final cumulative final assessment of models (especially expensive and multifunctional); cheap models need substantial improvement and increase in their capabilities while maintaining their price category.
The analysis of the received results (final estimations) shows that the price of the device plays an extremely important role.In conditions of a significant decrease in the purchasing power of a mass buyer in Ukraine, the minimum price becomes the main competitive advantage in a comparative choice (which is understandable and quite predictable).Therefore, in the ranking of positions from the second to the fifth occupy cheap models of diagnostic scales.And only in the first position is an expensive model.This is due to the fact that almost all models (both expensive and cheap) perform weighing and calculations for three or four basic parameters.
And numerous additional service opportunities and convenience attract little to the consumer (in conditions of its limited funds).Therefore, the buyer chooses the cheapest models that provide basic measurements.The client cannot does not want, is not ready to overpay for various additional possibilities of the devices.
Only the perfection of the model, the maximum possible service options, high-quality manufacturing and excellent design, a reputable manufacturer (brand), a long-term warranty and a well-organized service can attract the consumer to more expensive models of diagnostic scales.It shows an example of a model that, with a slight overweight (only 0.3 points), came out in the first place as a result of calculations of the integrated consumer appraisal.That is, there are advantages in the market either cheap models (with functionality limited to only a few of the most basic features) or ultra-modern (advanced technically, functionally and image fully) expensive models of diagnostic scales.
To conclude the discussion, we should dwell on the limitations of both the model itself and the specific numerical results obtained.A sensitive limitation of the model as a black box is that if the ratio of importance (for the consumer) of individual criteria changes, it is necessary to make changes directly to the model itself.
The emergence of new parameters also requires adding them to the model (describing them with widespread and available) various household technical devices that can objectively measure various physical indicators.One such device is the floor scale.There are three groups of household body floor scales in the market: simple mechanical scales, conventional electronic, and diagnostic (smart) scales.The market offers a large number of models from various manufacturers, with different functional capabilities, the ability to determine a lot of useful information about the state of the body Simple and accessible are mechanical scales.More functional are electronic scales, which often have various additional functions.However, the most modern representatives of electronic scales are the recently developed so-called diagnostic (smart) scales.They determine not only the mass but also analyze in sufficient detail the composition of the human (user) body during weighing.
output parameter: Total score is 6 points.It can be seen from the figure that depending on the specific (clear) values of the input parameters (characteristics of a concrete device), certain decision rules are working (activated).The resulting integral estimate is calculated as the coordinates of the center of mass of the figure, which is formed by summing the estimates according to individual rules (which are active for a particular set of input parameters).

Figure 2 .
Figure 2. Activating decision rules and obtaining a final estimate Source: Author's elaboration

Figure 3 .
Figure 3. Surfaces of fuzzy output for each two pairs of input parameters.Source: Author's elaboration

Table 1 .
The evolution of the positivist paradigm.

Table 2 .
Black box model for customer behavior.

Table 3 .
Black box model for customer behavior.

Table 4 .
Buyer behavior and involvement.

Table 5 .
Characteristics of potential scales buyers.

Table 6 .
Parameters of the person body composition for diagnostic by smart scales.

Table 7 .
Main criteria for consumer choice of diagnostic scales.

Table 8 .
Scoring of separate components and parameters.

Table 9 .
Components for assessing consumer characteristics of diagnostic-analyzers scales.

Table 10 .
Numerical values for membership functions for input and output variables in the model.

Table 11 .
Generalized evaluation of the examined diagnostic scales.