Analysis and Measurement of Parameters of Quality of Life in Informal Settlements Surrounding of Tehran Metropolis

Quality of life is a concept used to describe the development of the welfare of society, and improving the quality of life is one of the most important goals of governments around the world. Informal settlements, as one of the most vulnerable urban areas, are always in unfavorable conditions in terms of various social, economic, and physical indicators. Therefore, the main purpose of this study is to investigate the status of various quality of life indicators in informal settlements around the metropolis of Tehran in Iran. This research is descriptive, analytical, and correlational based on primary data in which the initial data are collected through the documentary and survey (field) method using a questionnaire. The collected data were processed by SPSS and SmartPLS software. Based on the results of the t-test, quality of life indices in informal settlements around the metropolis of Tehran, on a Likert scale with an average of 23.2, is at a low level. Also, the results of the PSL path modelling and multivariate regression test show that increasing the quality of social, economic, physical, service, and access indicators, in terms of residents, has the greatest impact on improving the quality of life of this urban fabric and security index. It has the least impact. There is also a significant relationship between indicators, and the mental perspective of citizens changes under social, service, economic, and physical conditions.


Introduction
e 20th and 21st centuries have seen the rapid growth of urbanization and the sudden increase in slums, with only 13% of the world's population living in cities at the beginning of the industrial age [1]. While, now, by 2020, the world's population has reached 7 billion and 817 million people [2] in which only 3.1 billion live in rural areas [3].
is has led to excessive attention on urban areas and the accumulation of wealth and services in these settlements, while the rural areas have become more deprived. As a result of this escalation of economic, social, and welfare inequalities between urban and rural areas that have occurred in the last century, the city environment has become more attractive to immigrants in a way that many of these immigrants prefer living in the slums of the city rather than living in rural areas. In fact, due to the high cost of housing and financial inability, as well as the low level of technical skills in immigrants, most of them inadvertently go to areas of the city that have minimal facilities, services, and environmental quality [4].
Many people continue to live in such conditions because they are trapped in poverty and are unable to move towards a formal urban lifestyle due to the competitive market forces that exist in the city [5]. is the start point for developing outskirt urban textures that lack any environmental services and quality per se. ese settlements grow at the outskirt of metropolises under the title of informal settlements.
Informal settlements have been recognized as a global challenge for decades. In countries such as India, Egypt, South Korea, and Iran, such settlements represent a method of urbanization [6,7]. According to the studies of the Ministry of Housing and Urban Development, studies have been conducted so far about informal settlements in 77 cities in the form of 851 informal neighbourhoods with an area of 52,443 and a population of more than 5,900,000 people. Tehran, Mashhad, Zahedan, Tabriz, and Isfahan are the cities with the highest number of informal settlements, respectively, and in need of improvement [8]. Despite the long history of urbanization and recognition by government policies, living conditions in these areas are very difficult [9]. Despite years of efforts to strengthen the urban status, in the current situation, these neighbourhoods are commonly identified with severe insecurity and vulnerability in the social, economic, and physical sectors. Residents of these urban neighbourhoods also struggle with basic services such as water, health, electricity and environmental hazards, and air pollution [6].
Inadequate urban environmental conditions and their ongoing consequences on quality of life in informal settlements have become the most controversial aspect of cities. Cities and towns in developing countries such as Iran are growing rapidly [10].
In informal urban settlements, the rate and scale of physical growth and development and population density have exceeded acceptable standards of public health, physical infrastructure development, environmental safety, and sustainable economic growth. erefore, the quality of life is significantly reduced compared to other areas [11]. erefore, a comprehensive study and assessment of living conditions should be conducted with scientific criteria to plan for the improvement of living conditions based on a comprehensive cognitive. In the meantime, the criterion of quality of life can indicate the achievement of such a goal because it is a comprehensive concept that covers various aspects of human life [12]. Quality of life is one of the most important issues facing the world today. Also, improving the quality of life is one of the most important goals of different governments and states [13].
In the past few decades, paying attention to the quality of life and improving it in urban and rural settlements has been one of the main goals of human development programs and has continually influenced the policies of countries around the world [14,15].
e term "quality of life" is used to assess the general well-being of individuals in societies, but its meaning is very complex and very comprehensive and varies according to the time and beliefs of the individuals [11]. Quality of life is a concept to show how to meet human needs and a criterion for understanding satisfaction or dissatisfaction with various aspects of life [16].
e World Health Organization defines the quality of life as people's perception of their position in life in the context of the culture and value systems in which they live and according to their goals, standards, expectations, and concerns [17]. According to Ghasemi et al., the quality of life depends on how people live, feel, and understand daily life.
is includes aspects such as health, education, housing [18], employment, and participation in decision-making [18][19][20]. Dovey points out that quality of life is a term that has emerged as a concept of living conditions, health and physical safety, and mental and social ability [21]. Richards and Mutsonziwa consider the level of quality of life as how each individual or group views the society [22].
As mentioned, the world's urban population is about twice that of the rural population, and it is predicted that, by 2030, this gap will increase even more in developing countries [23]. One of the consequences of these population shifts and urbanization is the increase of urban poverty and the physical development of cities [24]. e emergence this phenomenon is informal settlements with the main feature of urban poverty and informal development of the city body [25]. According to the United Nations estimations, around 1 billion people, 14 per cent of the world's population, live in these suburban areas, which can be doubled by 2030 [26,27].
Ono introduces these settlements in Nairobi as amazing spaces with planned growth and high population density, which accommodates most of the poor [28]. Verma finds living conditions in Indian slums very difficult. According to him, quality of life is summarized in a wide range of fields such as international development, health, political sciences, urban environment, education, leisure, and social affiliation [29]. Dovey et al. believe that a wide range of social, economic, and political complexities will lead to the creation of informal settlements around metropolitan areas [30]. ese settlements are generally defined as the rapid, unauthorized, and organic growth of new urban neighbourhoods. ese settlements have always been considered as an attraction for migration and affordable housing in the face of a lower quality of life [31,32].
All these approaches are in line with achieving sustainable urban development. Quality of life, in the category of sustainable development, emphasizes continuity, coordination, and stability of development, including the economy, environment, culture, living conditions, and other factors [33]. Quality of life findings can be used to identify past policy strategies and design future planning policies [34]. Such design has some fundamental structures and it can be done using many artificial intelligence approaches in intelligent systems [35][36][37][38][39][40][41][42], which we cannot review all of them as it goes beyond the scope of this research. Santos and Martinez point out that local social participation in quality of life studies can be an important support for setting longterm policies and goals [43]. e issue of quality of life has entered the urban planning and development literature since the 1960s. is view was further explored by geographers such as Harvey and Smith [44,45].
In Iran, as in other middle-income developing countries, rapid urbanization in the last five decades has led to the expansion of informal settlements in areas around metropolitan areas [46]. Among the big cities of Iran, the metropolis of Tehran is facing more informal settlements and self-growth areas in its outskirts or middle, rather than other cities of the country due to various factors such as being political-administrative central of the country and the concentration of the most economic, industrial, and service activities in it. e emergence and growth of informal settlements in Iran is the result of government policies since 1980. During this period, incomplete efforts have been made to improve the conditions of these settlements. However, the main question is what indicators are important in improving the conditions of informal settlements and why? e day-to-day growth of these areas and the increasing complexity of the social, economic, physical, service, and security situation show that we are paying attention to the different dimensions of these urban contexts.
e main approach of this study is to investigate the quality of life in these settlements and the impact of quality of life indicators of improving the situation in these areas.
e varieties of indicators used in urban quality of life studies are innumerable. is is obvious given the multidimensionality of the concept of quality of urban life. It is generally assumed that each indicator reflects the size and importance of a particular dimension of the quality of urban life. is assumption is based on the fact that the quality of urban life can be separated into a set of components or dimensions, and if these components are properly combined, a value for the quality of urban life can be obtained.
In this study, various indicators of quality of life have been studied, and finally, according to the type of context studied, the 5 main physical, access and service, security, social, and economic indicators in 13 components ( Figure 1) have been selected. ese indicators of Islamshahr are considered as an informal settlement around the metropolis of Tehran in Iran. As a result, it seems that, in order to formulate an appropriate strategy, we need more work and research in various fields in these urban areas. erefore, the present study attempts to measure the criteria and indicators related to quality of life at the desired neighbourhoods ( Figure 1) and specify the lack or suitableness of each of the indicators. e indicators presented in Figure 1 have been examined based on the current situation and the indicators presented in previous studies, and finally, by matching all the indicators, 5 indicators in 13 criteria have been selected. ese indicators are the basis for compiling a questionnaire in the form of related questions on which the collection of study data has been done.

Materials and Methods
e study, to develop criteria and indicators of quality of urban life and upgrading these criteria in informal urban contexts, requires a comprehensive approach to planning and study that while identifying and classifying criteria and indicators of quality of urban life, there needs to be a causal relationship between these indicators. e research methodology in the present study is descriptive, analytical, and correlational and the data collection method is a documentary and survey in which the survey part has been done through a questionnaire method.
To assess the quality of life in informal and peripheral settlements around the metropolis of Tehran, with emphasis on Mozaffariyeh, Mianabad, and Ziaabad areas in Islamshahr, five main dimensions of physical, economic, social, services (accessibility), and security have been used. Each of these dimensions has subcategories that have been explored. e sampling method was simple and random and the sample size was estimated using the Cochrane methodology.
According to the census of the Statistics Center of Iran in 2016, the population in the three mentioned neighbourhoods of Mianabad, Ziaabad, and Mozaffariyeh are about 53234 people [8]. is population is considered as a statistical population in which a statistical sample of 381 people was selected and a questionnaire was distributed among them.
Collecting and preprocessing of data is a very crucial step in any statistical or analytical analysis [47][48][49][50][51][52]. e data obtained from the questionnaire were analysed using SPSS software and statistical analysis of PLS. In the section of descriptive statistics, abundance, frequency percentage, mean, etc., eere used, and in the inferential statistics section, due to the conversion of research variables into quasi-distance variables, in order to calculate the importance or existence of any feature, numbers of 5, 4, 3, 2, and 1 were, respectively, assigned to very high, high, medium, little, and very little options; then, the score of each option was calculated by multiplying the frequency by the score of each option. en, with the option's scores, the score of each question was obtained, where average scores were calculated by dividing the sum of the points by the number of people who answered to that option. Given that the average score of each question is a number between 1 and 5, so this criterion was used to assess the importance of questions or options. en, some parametric tests such as t-test and multivariate regression in SPSS software environment have been applied [53] and PLS path modelling has been used with the help of SmartPLS software [42,[53][54][55][56][57][58]. Cronbach's alpha test was used to calculate the reliability of the questionnaire questions in which the reliability score is equal to 0.89 and at an acceptable level [59][60][61][62][63][64][65].

Results and Discussion
Between 1992 and 2007, with the development of Tehran metropolis and the filling of vacant lands, the influx of capital and special social groups into the almost untouched suburban lands of the southern and southwestern part of the metropolis of Tehran began; physical disorders peaked and construction of uncoordinated textures of sheds, informal urban textures, annexation in villages, and self-growth cities was observed in abundance in Tehran.
As of now, despite serious measures to prevent illegal construction, the destruction of gardens and land occupation has continued. Due to the indecision of landowners and lack of appropriate action by the municipality, a significant part of the area was separated and was built in the form of disordered and self-growth textures and sheds which cause the development of the urban area in an attached or detached from around Tehran as much as possible.
Since the quality of life is a relative issue and the individual characteristics and living conditions of each person have a great impact on the quality of life of each person, part of the questionnaire is dedicated to descriptive information. e descriptive statistics of the research include age, gender, marital Mathematical Problems in Engineering status, education, homeownership, length of residence in the neighbourhood, age of the residential house, type of vehicle, and reason for living in these contexts, which is shown in Table 1.
Here, we have examined in detail some of the descriptive information and personal characteristics that are more important in the discussion of the quality of life.
In terms of gender, 62.4% were male and 37.6% were female. In terms of job difference, 2.3% of the samples were employees, 40.2% were self-employed, 14.7% were retired, 5.7% were student, 25.5% were housewives, and 11.7% were unemployed.
In terms of the residential house age, the status of respondents was as follows: age of their homes of 2.8% was between 1-5 years old, 47% was between 5-10, 8.1% was between 10-15, 12.3% was between 15-20 years, and 72.1% was more than 20 years and in terms of ownership, and 82% of respondents were landlords and 18% were tenants.
Also, the average of each quality of life indicators is shown in Table 2.

Measuring the Dimensions of Quality of Life from the
Perspective of Informal Residents. In this research, the average of the sample is compared with the value of 3, which is considered the average value. If the average of each index is significant and has a significant difference to the value of (P < 0.05), it indicates that the level of satisfaction with the quality of life is below average.
To assess the level of quality of life in the intended contexts around the metropolis of Tehran, indicators, including physical, economic, social, access services, and security have been used. e one-sample test was used to assess the status of each indicator and the level of satisfaction of each. e T-test was also taken for each of the subindicators and their sum was analysed. Table 3 summarizes the obtained results.
As can be seen in Table 3, the quality of life in three neighbourhoods of Mianabad, Ziaabad, and Mozaffariyeh is low based on the results of the T-test. Also, in terms of indicators and subindicators, the state of satisfaction with physical, economic, social, access services, and security features has been significant and shows a low quality of life in all aspects of quality of life.
e results show that, in all factors affecting the quality of life, the actual mean value is greater than the assumed mean; in other words, the average level of life satisfaction in the dysfunctional urban context is considered as the T value. Since, in informal settlements, renovations or appropriate constructions are rarely done (mostly due to the poor economic situation of the residents of these neighbourhoods), so most of the texture of these neighbourhoods is worn out and based on the average, minimum satisfaction is in the physical dimension. Also, due to the residency of lowincome people and immigrants and vulnerable groups (addicts) in these neighbourhoods, the level of economic satisfaction is very low.
However, on the contrary, due to residents pressured by the government through various laws and different organizations, as well as their social distance from urban life and low level of access to services, there is a high level of solidarity and unity between them, and the level of social solidarity is high in this area.
Since, in these neighbourhoods, services are not provided by the government and the municipality, due to the informal recognition, and also insecure places, due to the presence of criminals and addicts, and the level of satisfaction in terms of access services and security is low.

Determining the Share of Important Indicators in the Quality of Life (Using Multivariate Regression).
One of the important defaults of linear regression is related to the distribution and dispersion of variable data in which data of the research variables should be normal or close to normal [66][67][68][69][70]. e Kolmogorov-Smirnov test is used to solve this problem.
e results of the Kolmogorov-Smirnov test in Table 4 show that the distribution of research data is normal and has a normal statistical proportion so that the statistical value of this test for the data of this research is equal to 0.792. R, which is sometimes known as the correlation coefficient, fluctuates between zero and one. e closer the value of this correlation is to one, the stronger the correlation is between the independent variables and the dependent variables. According to Table 5, R value is equal to 0.921, which indicates an acceptable and high value. R square is the coefficient for determining the research indicators, and the  value of this coefficient also fluctuates between zero and one, and the closer it is to the value of one, the more it indicates that the independent variables were able to explain the amount of the dependent variable. erefore, since the coefficient of determination is equal to 0.868, it shows that approximately 0.866% of the total changes in the level of satisfaction with the quality of life in informal contexts around the metropolis of Tehran can be determined with the five dimensions of this research.
We have followed fair comparison rules to reach unbiased results and comparisons regardless of the computing environment [71][72][73][74][75][76][77]. e sig value of the analysis of variance column was used to check the correctness of the regression model fitting. As shown in Table 6, the value of the significance level is equal to zero, and since the value obtained is less than 0.05, it follows that the used regression model is significant and a good predictor of the dependent variable which is quality of life.
Since the scale of independent variables is often composed of different units in regression analysis, the standardized regression coefficients help the researcher to determine the relative contribution of each independent variable in explaining the changes of the dependent variable by considering other specific independent variables.
In this test, the higher the beta coefficient of a variable, so is its role in predicting changes in the dependent variable. According to the significance test of the coefficients, it can be concluded that all the dimensions of the research have a positive effect on the quality of life. Also, standard coefficients have been used to compare the effect of independent variables on the dependent variable which is quality of life.
Based on these obtained coefficients, the share of each of the considered dimensions to measure the quality of life in the informal settlement of informal neighbourhoods around Tehran was the highest, respectively, on the social dimension with a standard coefficient of 0.48, economic dimension with a standard coefficient of 0.443, physical dimension with a standard coefficient of 0.327, service and access dimension with a standard coefficient of 0.328, and security dimension with a standard coefficient of 0.233.
ANOVA analysis also shows whether the regression model can significantly and appropriately predict the changes of the dependent variable and according to Table 6; the obtained sig value is less than 0.05, which indicates that the used model is a good predictor of the quality of life's variable. It is very vital to have a clear conceptual model and determine the best way for measuring and assessment of the qualitative data [42,55,[78][79][80][81][82][83][84].] e conceptual model tested in the standard mode or PLS algorithm and the path coefficient are presented in Figure 2. e numbers shown on the path of the structures together are called the path coefficient. is number represents the standardized beta in the regression or correlation coefficient of two factors and is presented to examine the degree of the direct impact of one variable on another variable. e numbers displayed on the path between operations and indicators represent the factor load in reflective models.

Measuring the Impact of Indicators on the Quality of Life
According to Figure 2, which shows the status of the research, the measurement model in the standard mode, and according to the values of path coefficients that represent the standardized beta in the regression or correlation coefficient of two instruments, we can measure the effect of each of the independent variables which are the five dimensions of quality of life in this study on the dependent variable; the impact of these dimensions can also be ranked.
Based on the internal or structural model of the research, the social dimension of quality of life with a coefficient of 0.451 had the greatest impact on quality of life in the studied area. en, the economic dimension with a path coefficient of 0.436, the economic dimension with a path coefficient of 0.305, and then services and access dimension with a path coefficient of 0.232 were placed in the next ranks, and finally, the security dimension with a path coefficient of 0.215 had less impact on quality of life in the studied area.

Conclusions
According to the results of the research, the quality of life in informal and marginal urban areas is not very favorable so that the average quality of life indicators in these urban neighborhoods is equal to 2.34 in the Likert range (1)(2)(3)(4)(5), which is lower than the average. Also, the results of the T-test show that the level of satisfaction with the quality of life in these urban areas is in an unfavorable situation.
T-test on indicators and subindicators demonstrate that the level of satisfaction with all aspects of quality of life is low. Also, based on the results of the regression test and based on the obtained beta coefficients, the share of each of the dimensions intended to measure the quality of life in informal settlements around the metropolis of Tehran, respectively, are a social dimension with a standard coefficient of 0.488, the economic dimension with a standard coefficient of 0.443, the physical dimension with the standard coefficient of 0.23, the service and access dimension with the standard coefficient of 0.238, and the security dimension with the standard coefficient of 0.233.
Also, based on the results obtained from the structural PLS model, the social dimension of quality of life with a path coefficient of 0.451 had the greatest impact on quality of life in the studied area. e economic dimension with a path coefficient of 0.436, the physical dimension with a path coefficient of 0.305, and then services and access dimension with a path coefficient of 0.232 were placed in the next ranks; finally, the security dimension with a path coefficient of 0.215 had less impact on quality of life in the studied area. erefore, by recognizing the impact of each of these components and their prioritization and planning to   improve these components, the level of life satisfaction in the studied areas can be increased. By examining this model in detail, the most important factors that have reduced the quality of life in this neighborhood can be related to economic and access services' indicators, which with an average of 1.65 and 1.68, respectively, had the lowest level of satisfaction among residents. Most of them work in informal and false parts of the city, such as peddling, which has led to low household income and lack of job security.
Regarding the service and access indicators in these neighborhoods, due to its informal settlement, they are not in a favorable situation in terms of having facilities and municipal services. e sum of these factors has caused the relative deprivation of neighborhood residents from urban facilities and services. However, the highest level of quality of life indicators is related to the social index, which with an average of 3.71 in the Likert spectrum has favorable conditions compared to other indicators, in which one of the important factors, in this case, is due to the long history of people living in this neighborhood; immigration and low immigration of this neighborhood has caused the people of the neighborhood to be highly dependent on each other.
According to the materials presented in the previous sections, in the study areas around the metropolis of Tehran, there are dysfunctional urban contexts, which are also considered informal settlements.
Also, due to the high participation capacity at the neighbourhood level, due to the low level of household income, some cases lack titled deed, weak infrastructure and municipal services and lack of licenses for construction and improvement or renovation of houses, lack of sufficient democratic institution for reflection of citizens' opinions to the responsible institutions, insufficient trust in managing the unfavorable physical condition of buildings, etc. e possibility of improving the quality of life in these urban contexts is facing major problems. Now that a general understanding of the characteristics of these urban contexts as well as the level of quality of life indicators in this informal settlement context has been determined, clearly, it does not make sense to abandon it in the hope of long-term economic plans, in which their realization is in a haze of ambiguity due to their own complexity or waiting for these areas to reorganize on their own. erefore, it is hoped that the authorities will take steps to organize and solve the problem of this settlement by using the internal potentials of these contexts and relying on public participation. erefore, the most important strategies that can be mentioned about improving the situation of these neighborhoods are as follows: e most important solution and the first step in improving the situation of this settlement and increasing the quality of life indicators in these areas should be considered as building trust between the residents of this settlement and urban management so that the involvement of personal and group participation of residents in activities such as renovation and empowerment carried out by urban organizations can be increased. e city administration must first allocate a certain investment to improve the physical and quality of public spaces in order to gain the trust of the residents of this neighborhood towards the municipality and urban management and, in the future, create a good opportunity to improve other spaces. In fact, increasing the quality of public spaces in this place provides a good intention of trust and interaction for residents towards urban management and the implementation of empowerment and renovation projects. Create adequate support for receiving bank facilities and reviewing all laws and regulations restricting the access of low-income groups to official facilities and credits and applying appropriate initiatives with the lack of ownership and income fluctuations of the informal sector. Empowering the neighborhood by creating jobs for residents and preventing them from being attracted to mendacious jobs, one of the most important strategies of it, is the development of the local economy.

Data Availability
e data used to support the findings of the study are available from the corresponding author upon request.

Conflicts of Interest
e authors declare that they have no conflicts of interest.