The effect of urban livability factors on the present situation using Structural Equation Modeling of Partial Least Squares (Case study: district of Tabriz city)

Introduction
The concept of a livable city means to be suitable for living or habitable, which has been very strong today by expanding and intensifying the problems human societies and the loose of quality of life. The word "livable cities" for the first time in
1970 by the national Arts organization in order to achieve their urban ideas and looking for it by other centers and research organizations such as the environmental protection organizations that has done extensive studies regarding the most of American cities was gone. Following the influence of this word in the literature related to this field can be searched in 1975 and the writings of William Marlins on the fields of livable  in Saturday Review and Christian Science Monitor. Today, by expanding the problems of human societies and increasing their day to day (problems) has been greatly increased the quality of life indicators of residents of different places. Tabriz is one of the oldest cities in the country with regard to the historical, economic, cultural, health and industrial backgrounds of Tabriz metropolis, which has turned the city in to the first city in different fields. Today not only does not upgrade this roles and functions but also is in annihilation state.
Because of its complex and multi-dimensional conceptual and its patterns vary from one region to another. So far a comprehensive model of the impact of the overall livability of cities on the present situation and the relationship between them is not defined. This paper tries to measure the present situation based on the appropriate models of Tabriz and the effect of the dimensions of livability on the situation in objective models based on scientific methods.
Hence, the main objective of the present study was to determine the level of livability indices based on their impact on the situation in Tabriz metropolis using structural equation modeling technique.
The output of this research helps urban managers and planners have a bright picture of the ecological sector of Tabriz metropolis.
This article has been formulated based on scientific study and tracking to answer the following question. What conditions is the current condition of the city of Tabriz in different dimensions? and which indicators should be the first priority of the planners be given the amount of  their impact on the present situation to achieve urban livability in Tabriz  metropolis?
Methodology
This research is applied in terms of nature and is a descriptive-analytic method. The instrument was a questionnaire the statistical population in this research are the experts and urban managers with complete familiarity with the situation of each region, has a number of 140 people. According to the   volume of society and Morgan table, 104 people selected by non-linear snow bullets and the question have taken place. Then the statues of livability using single sample T-Test and relationship between dimensions and livability in  dices is analyzed with structural equation modeling whit Partial least squares method(PLS).
Results and discussion
Due  to the increasing development of the life- level of Tabriz metropolis, requiring the main indicators and influence on the existing situation and communication between them.
This research has provided new insight in to the livability of  Tabriz metropolis that will detect the priorities of action in the decision space.
Study of analysis of the present analyses regarding the current situation of Tabriz's livability in different dimensions generally, the average obtained in all dimensions (urban services and infrastructure, urban environment, urban economics, urban management, urban history and the urban community) were lower than the average  and the results are not statistically significant only for urban community index that the results of this indicator are not generalized.
Also, prioritizing  indicators due to their impact on the present situation to achieve urban livability in Tabriz metropolis shows that highest share of urban services and infrastructure are (providing daily necessities in the neighborhoods, highways access, access to other neighborhoods in the city, access to workplace, the quality of
water,  electricity, gas and internet, Bank, quality of public transportation in neighborhoods, public transport work hours and distribution of public transport stations), that pays  attention  to urban managers and planners.
Research findings show the current condition of Tabriz's livable situation according to the average of all ten areas in all 
dimensions is low that it has alignment with the findings of  Rashidi and colleagues (1395) who have assessed  the livability of Tabriz region in comparison with the Osku, Azarshahr, Bostan Abad, Tabriz, Shabestar and Herris.
This findings with the findings of Ali Akbari and Akbari (1396), which has recognized the equitable distribution of facilities and services identified the main livability of the city of Tehran, the study of Aluria (2017) that the factors  affecting  on the quality of life of residents has expressed the distribution of urban services and also the ministry of  Sustainable Management in India (2018) that physical index (with 45%) highest ranking in the livability standards.
Conclusion
This research, based on structural equations analysis shows that the services and urban infrastructure have the highest effect on the present situation of Tabriz metropolis livability
In any attempt to improve the livability of Tabriz, it should be considered the role and position of this indicator.
The results show that all aspects of livability in Tabriz metropolis have low average. The results of the model also show that among the influence factors on livability status, "urban infrastructure and services" and "urban environment", "urban management", "urban history" and "urban community" factors have a direct and meaning full effect, In the meantime, the  "urban infrastructure and services" factor has the greatest impact which has a motivation of Tabriz  metropolis livability. As a result, any program and attempt to initiate and upgrade of the livability of Tabriz status need attention to the key role of these factors.
But what is particularly the achievement of the present study is preparation of appropriate bio-model with the new scientific methodology Partial least squares (PLS) based on present conditions.