1. Introduction
The aging population has become a serious challenge to global social development. China is the only country in the world with an elderly population approaching 250 million, and old-age support has become a major responsibility for Chinese families and society [
1]. With the implementation of the 13th Five-Year Plan for Construction of Social Pension Service System, the old-aged service system that is based on home-based old-age care and that has relied on the community and is supported by institutions has initially taken shape [
2]. This new pension model combines home-based care and community service organically so that elderly people can not only receive proper life and spiritual care, but also continue to live in a familiar community environment [
3]. Against this background, the quality of the living environment has become an important pursuit of elderly groups to improve the quality of life in their later years, especially elderly people who have the ability to move and who prefer to participate in outdoor activities that can meet their physiological and behavioral characteristics, which puts forward higher requirements for the construction of a community environment that suits elderly people. Thus, research on the assessment of suiting the community environment to elderly people has an important reference value for urban residential environment planning, the regional development model and the development direction of urban real estate, and caters to the will of many elderly people to provide for the aged at home, which has positive social significance [
4].
In the 1950s, Doxiadis first proposed the concept of “human settlements science”. Since then, scholars have focused on the study of urban livability and the suitability of the community environment for elderly people. Current studies mainly focus on the influencing factors and evaluation methods of a suitable community environment for elderly people to analyze the degree of the suitability of the community environment for elderly people. Rostron put forward the corresponding design principles for the external environment of elderly people’s residential areas from the aspects of a site layout and detailed design based on the perspective of the behavioral psychology of elderly people [
5]. Salzano explored the concept of livability from the perspective of sustainable development and considered the livable environment of elderly people from the perspective of the sustainable development of urban construction; he believed that factors such as the interpersonal relationships of elderly people, construction of community environmental facilities and location selection would affect the living environment of elderly people [
6]. Douglass advanced the basic conditions for the harmonious development of livable cities from the perspective of a correlation among humans, the environment and society [
7]. Through studying a comprehensive environmental assessment of elderly communities, the British Economist Intelligence Unit has created an index system for evaluating urban livability that included three groups of indicators, namely, health and safety, culture and the environment, and infrastructure [
8]. Harvey proposed to use a geographic information system, an Internet survey and social media to investigate the physical characteristics on the spatial scale of the block and residents’ satisfaction to effectively measure the livability of urban communities [
9]. In the 1990s, Wu began to conduct relevant research on urban human settlements, established a scientific and theoretical framework for the environment of human settlements, and advanced the principle of people-oriented environmental construction [
10]. Based on a survey of the living environment of elderly people in Beijing, Qu compiled a localized gauge that is divided into four dimensions, including a housing environment assessment, community environment assessment, service environment assessment and interpersonal environment assessment for evaluating the living environment of elderly people in cities. It is clear that the key task of constructing a livable community for elderly people in Beijing is to improve the construction of accessible community access, sports venues and other related environmental facilities [
11]. He and Wei analyzed the status of building community environment renovation for senior people and raised environment renovation strategies and service facilities configuration [
12]. Li proposed construction strategies of endowment facilities during community restructuring [
13]. Many factors affect the suitability of the community environment for elderly people, but it is not advisable to integrate them all into an evaluation index system. Therefore, constructing a community environment evaluation index system suitable for elderly people should be based on the specific situation.
Apart from studies on the factors that affected the suitability of the community environment for elderly people, scholars have also paid attention to the evaluation methods on the suitability of the community environment for elderly people. Wu and Tang identified four evaluative objectives, road site adaptability, facility universality, space diversification and environment gracefulness, from the perspective of a rehabilitation landscape and 15 evaluative factors. They also established an evaluation index system for the restoration of the external environment of elderly apartments by using the analytic hierarchy process (AHP) [
14]. Lu et al. used principal component analysis to study the quality and spatial pattern of the residential ecological environment in the central city of Hangzhou and obtained the measures that needed to be adopted to protect and repair the fragile zone of the residential ecological environment [
4]. Sang et al. established an evaluation index by using qualitative–quantitative methods to test the effectiveness of the suitability of an elderly urban construction index system [
15]. Yu and Hu constructed an index system and a calculation model to scientifically evaluate urban leisure Greenland adaptability for elderly people [
16]. Gupta sorts green human resource management using the best-worst method (BWM) [
17]. Rezaei compared with other multi-criteria decision-making (MCDM) methods and proposed that the BWM method needs less data and pairwise combination, and its result is more reliable [
18]. Panmucar et al. employed the full consistency method (FUCOM) in ranking of traffic demand management measures [
19]. Eghbali-Zarch et al. used the step-wise weight assessment ratio analysis (SWARA) method to compare and rank the effects of anti-diabetic medication objects, and the validity of the model in determining weights was verified [
20]. Mardani et al. categorized the literature and did systematic research on the classification of the MCDM methods, including the new SWARA method [
21].
Until now, studies on the evaluation method of the suitability of elderly people’s community environment are in the early stage, and the current evaluation methods mainly use quantitative analysis to analyze the degree of suitability of the community environment for elderly people. Although there is abundant literature and experience in the area of community environment research at home and abroad, few studies have been conducted on evaluating the environment of outdoor activities for elderly people. Although the Qingdao, Huzhou, Shanghai and Changning districts (among other places) have introduced an evaluating index system of old-age friendly cities, there are few evaluation tools for an elderly livable community, and the importance of a subjective evaluation of elderly people is seriously insufficient [
11]. In the selection of indicators, most of the classification indicators are based on the suitability of environmental human settlements, without considering the actual needs of elderly people from the particularity of their physiological and behavioral characteristics. When using mathematical models for evaluation, only some dimensions are often considered, and the comprehensiveness of the factors is not taken into account.
To fill this important research gap, in this paper, according to the four dimensions comprising site environment, road environment, ecological environment and green environment, a comprehensive evaluation index system including 39 indicators are constructed. Furthermore, using the method of AHP to calculate the weight of each indicator and the improved technique for order preference by similarity to ideal solution (TOPSIS) to evaluate the community environment, would clarify the community environment which is suitable for the old people to live in and move. The hybrid model of AHP–TOPSIS realizes the comprehensive evaluation of qualitative and quantitative indexes and avoids the defects of the single model. Our main contributions are the following: First, considering the factors of the community environment suitable for the aged, a relatively comprehensive evaluation index system is established; second, using the improved TOPSIS method to evaluate the results, the reliability and accuracy of the results are increased; and third, the reference opinions are given to the government and relevant departments in renovating the community environment and considering the living environment of the elderly.
The rest of the paper is organized as follows. In
Section 2, the comprehensive process evaluation index system of the suitability of an elderly community environment is established from multiple dimensions, which measures the level of community environment aging. In
Section 3, this index system calculates the weight of the indicators by using AHP and on this basis improves the TOPSIS method through a two-dimensional data space map to make the evaluation process more scientific and appropriate. In
Section 4, the validity and effectiveness of the method are verified by taking five communities in Wuhu City as evaluation objects. Conclusions and further studies are drawn in
Section 5.
3. The Improved TOPSIS Method
TOPSIS is a sequential optimization method for the similarity of ideal objectives. It is very effective in multi-objective decision-making analysis [
30,
31,
32,
33]. By normalizing the original data matrix after trends, the corresponding data matrix that is normalized is established, and the best and worst schemes are identified from many schemes. Then, the distance between all index values of each evaluation object and the positive and negative ideal solutions are calculated separately; thus, we can obtain the closeness between the evaluation object and the ideal solution, and the ranking is the basis for evaluating the quality of the object. Because the TOPSIS method uses the relative approximation between ideal solutions to arrange the priority order among different schemes, the TOPSIS method is improved by referencing the literature to avoid contradictions. A two-dimensional data space method is established by changing the closeness degree between the final objective and the ideal solution into all the index values of the known evaluative objects and the distance between the positive ideal solution and the negative ideal solution to relieve the contradiction and decrease order problems. The flow chart of the improved TOPSIS algorithm is as follows (
Figure 2):
First, M evaluation objectives are usually established to solve multi-objective optimization problems
, and each object is accompanied by an N evaluation indicator
. Second, relevant experts are invited to grade the evaluative indicators (including quantitative and qualitative indicators), and the results are then presented in the form of a mathematical matrix, which establishes the following characteristic matrices:
After establishing the primitive characteristic matrix, follow the below steps for analysis.
Step 1: Construct a normalized matrix.
By using Equation (2), the original matrix is normalized to obtain the corresponding matrix:
where r
ij means the value of the i evaluative object on the j index.
Step 2: The weights obtained by the AHP method are combined with the normalized matrix and establish the weighted decision matrix A
. Multiply the weight vector A =
obtain a weighted standardization matrix as follows:
Additionally, it is noted that the positive ideal solution
and the negative ideal solution
of all indicators of each evaluative object are
where
.
Step 3: Calculate the distance scale.
The distance scale is the distance between the best solution and the worst solution of each scheme. It can be calculated by the n-dimensional Euclidean distance. Among them, the distance from the scheme to the positive ideal solution
is
, and the distance to the negative ideal solution
is
:
Moreover, , and is the approaching degree of each evaluation target to the optimal target. When the value is smaller, the evaluative target is closer to the optimal target, and the scheme is better.
Step 4: Establish a two-dimensional data space.
The two-dimensional data space of each evaluation objective (
) is established, and the point (Min (
), Max (
)) is set as the optimum reference point A (
Figure 3). Calculate the relative distance between each evaluative object and this point:
Step 5: According to the size of the Ci value, when the Ci value is smaller, the evaluative object is better; that is, the nearest point to the reference point A is the best. When the distance between the evaluation object and the reference point is equal, their coordinates can be directly compared on the two-dimensional plane of (, ), and the degree of the evaluative object can be judged according to the best principle that the evaluation object is near min () or max ().
4. Numerical Study
We chose five communities in Wuhu city, namely, Weixing Community, Dongfang Longcheng Community, Jinghu Century Community, Chery Bobo Community and Central Community as the objects of elderly community assessment suitability. We separately mark these . By using AHP to calculate the weight of each index, the result of the B-level single ranking weight is (0.333, 0.183, 0.381, 0.103)T, C-level single ranking weight is (0.151, 0.575, 0.274, 0.493, 0.137, 0.37, 0.529, 0.309, 0.162, 0.493, 0.137, 0.37)T, C-tier total ranking weight is (0.038, 0.144, 0069, 0.123, 0.034, 0.093, 0.132, 0.077, 0.041, 0.123, 0.034, 0.093)T, D-level single ranking weight is (0.493, 0.37, 0.137, 0.183, 0.381, 0.333, 0.103, 0.309, 0.529, 0.162, 0.265, 0.239, 0.372, 0.124, 0.316, 0.421, 0.263, 0.529, 0.309, 0.162, 0.75, 0.25, 0.333, 0.667, 0.212, 0.189, 0.518, 0.081, 0.152, 0.371, 0.066, 0.173, 0.142, 0.156, 0.667, 0.333, 0.137, 0.493, 0.370)T, and D-tier total ranking weight is (0.01, 0.031, 0.011, 0.015, 0.032, 0.028, 0.009, 0.026, 0.044, 0.014, 0.022, 0.020, 0.031, 0.010, 0.026, 0.035, 0.022, 0.044, 0.026, 0.014, 0.063, 0.021, 0.0258, 0.056, 0.018, 0.016, 0.043, 0.007, 0.013, 0.026, 0.006, 0.014, 0.012, 0.013, 0.056, 0.028, 0.011, 0.041, 0.031)T.
Based on the calculation of the weights of each indicator, the evaluation should be performed according to the following steps.
Step 1: According to the actual situation, each indicator is attributed with the relevant value, as shown in
Table 9.
Step 2: Refer to
Table 5,
Table 6,
Table 7 and
Table 8, 39 indicators corresponding to different evaluation levels. We have set the scores from
to
above (
= 1,
= 0.75,
= 0.5,
= 0.25, and
= 0). The scoring of each criterion is processed for numeralization according to five levels as shown in
Table 10.
Step 3: The normalization matrix of the above indicators is established as shown in
Table 11.
Step 4: The weights of each indicator are combined with the normalized matrix, a weighted decision matrix is established (e.g.,
Table 12), and the optimum and worst values of all indicators of each evaluation object are identified.
That is, the best scheme is:
Step 5: According to the best and worst value, the distance between each scheme and the best and worst solution is calculated. That is, the best solution is = (0.008, 0.065, 0.076, 0.056, 0.073. The worst scheme is = (0.089, 0.051, 0.028, 0.051, 0.036.
Step 6: According to Equation (8), the relative distance between each evaluation scheme and the point and ranked variables are calculated. Thus, according to the establishment of the two-dimensional data space map, and the relevant formula steps, the relative distance between the evaluation scheme and the point is calculated as Ci = (0, 0.069, 0.091, 0.061, 0.084).
The five housing estates are ordered according to the TOPSIS evaluative value: P1 > P4 > P2 > P5 > P3. From this, we can observe that Weixing Community (P1) is the best livable community that is suitable for elderly living and outdoor activities. Whether it is the road environment, site environment or landscape greening, Weixing Community is more consistent with the behavioral characteristics and activity needs of elderly people. Compared with Weixing Community, Jinghu Century Community (P3) and Central Community (P5) perform poorly in the aspect of community environment that suits the elderly. Jinghu Century Community has viaducts, trains and a high noise pollution ratio around its area, which has a certain impact on the outdoor activities of elderly people, while Central Community is located south of Wuhu City, which is developed. Because of the high cost of real estate development, the area of the community infield is limited, and there are fewer activities for elderly people, which do not meet the needs of outdoor activities of elderly people. Oriental Longcheng Community (P2) is located west of Wuhu City, near Tingtang Park, Wuhu. It has a good ecological environment. The site environment and green space environment can meet the needs of elderly activities. However, the road traffic environment in the community is general, which fails to achieve the continuity of accessible traffic and does not meet the needs of elderly people who move with a wheelchair. In the space layout of the site, the reasonable layout of dynamic and static zones is not fully considered.
Next, we use the traditional TOPSIS method to evaluate the suitability of five communities: The traditional TOPSIS method is to calculate the distance according to Equation (9), then the evaluation objects are sorted from large to small, where the bigger
is, the better the overall benefit. The calculation is as follows:
The result is Ci = (0.918, 0.440, 0.270, 0.477, 0.330). The evaluation results are consistent with the improved TOPSIS: P1 > P4 > P2 > P5 > P3.
The reasons for using the improved TOPSIS approach is that the improved TOPSIS considers the relative closeness degree of each evaluation object to the best and worst plan. Referring to the literature and examples, the disadvantage of using the traditional TOPSIS method is that the best solution and the worst solution of the decision-making scheme may change when new decision-making schemes are added, which leads to the reverse order of our ranking. If there are two evaluation objects about point A and point C symmetry, we have
and
, and if using the traditional TOPSIS method, the result will conclude that the two evaluation objects are of the same quality; however, this is not the case [
28,
29].
In order to increase the sensitivity of the data, we use the osculating value method to validate our model, and its Ci-value equation is
The result is Ci = (0, 7.552, 9.185, 6.427, 8.721). The principle of this method is to treat the positive and negative indexes in the same direction and calculate the distance between the evaluation object and the best and worst point, respectively. The closer the distance, the better the effect of the evaluation object. So, we come to the same conclusion as the above model; that is, P1 > P4 > P2 > P5 > P3. The validity of the evaluation results has been further proved.