A good educational environment and recreational center are guarantee to children's
healthy growth (Pluhar et al., 2010). Children's
recreational center plays a pivotal role in children's healthy growth (Davidson
et al., 2010). According to the research, children's recreational
center can reduce the possibility of children's obesity and depression (Trost
et al., 2011). Outdoor activities can promote confidence, social
skills, competition and collaboration in children by creating more opportunities
for children to interact with others (Humbert et al.,
2006). Urban green public spaces are important places for children to play
and have contact with natural environments (Lachowycz et
al., 2012). In recent years, the development of children's recreational
center has drawn increasing attention from the government. Many recreational
centers have been for children in urban green public space, which promotes children's
healthy development. However, there are still many children who do not enjoy
enough chances to do outdoor activities. Generally, there are problems on children's
recreational sites: (1) The quantity is small, and many urban green public spaces
do not reserve special sites for children's recreation; (2) low safety degree
indicates the presence of potential dangers. Accordingly, many parents would
rather their children to stay at home; (3) the recreational sites are poorly
designed, without fully taking into account of children's physical and psychological
characteristics thus are not attractive to children. Children have distinctive
physical and psychological characteristics from adults, which should be used
as the basis for the design of children's recreational sites.
Normally, the design proposals of children's recreational sites embody designer's
subject perception of the site conditions. Difference in the understandings
of designers will result in a diversity of design proposals. Children have preferences
to different recreational sites in urban green public spaces than adults do
(Lin et al., 2012). In real life, however, many
recreational sites cannot satisfy children's needs very well because of the
designers negligence. There is design method, but there is no fixed design
format. Although, children's recreation cannot be specified in a concrete form,
the intrinsic requirements with regard to children's recreational sites can
be obtained based on public survey, so as to promote the standardization of
the designs of children's recreational sites. Thus, it is very important to
employ appropriate methods to evaluate children's recreational sites in urban
green public spaces. Up to now, most existing evaluations on children's recreational
sites are case studies or qualitative studies. If there are multiple influential
factors involved, it will be very hard to make a choice among proposals. This
is why a scientific evaluation approach is important. The AHP-TOPSIS model is
a combination of qualitative and quantitative evaluations, providing basis for
optimizing design proposals of children's recreational sites.
RESEARCH CASES AND METHODS
Research cases: A curriculum design competition involving 28 senior
undergraduates majored in landscape design was hosted. The task was to design
a 2000-square-meter children's recreational site in Yulongwan community, Xinxiang
city, Henan province. The students were allowed to choose any location they
prefer within the community. The students were required to carefully analyze
the characteristics of children's recreational sites and submit detailed design
proposals within deadline.
Research method and procedures: The AHP-TOPSIS was used to evaluate
and sequence the 28 design proposals of children's recreational sites. AHP (Bao
et al., 2012) which is a combination of qualitative and quantitative
method, is used to measure the weight of each influential factor. TOPSIS, or
technique for order preference by similarity to ideal solution, is a method
which sequences the targets by its similarity to ideal solution to evaluate
The set of design proposals of children's recreational sites A and the set
of influential factors X were built. The calculating procedures are as follows:
Step 1: Creation of an evaluation matrix. By comparing n influential
factors pair wise on the scale from 1 to 9, a relative importance matrix B is
Matrix B has the following properties:
Step 2: Determination of the weight of each influential factor. The
method of summation is used to calculate the weights of influential factors.
First, matrix B is normalized column by column (making the sum of each column
Then the sum of each row is calculated:
Finally, the sum is normalized, and then the weight vector Wj of
each factor is obtained:
Step 3 Consistency check: Consistency check on matrix B is performed.
First, the maximum characteristic root λmax of matrix B is calculated:
Then C.I. (Consistency Index) is calculated:
Finally, C.R. (Consistency Ratio) is calculated:
where, the average random index R.I. can be obtained by checking Table
1. When C.R.<0.1, the consistency check is passed. Otherwise, the experts
need to modify the relative importance of the factor.
|| Average random index
Step 4: Creation of weighted matrix first, the scores given by experts
are transformed into matrix A.
Then, the matrix is normalized:
Step 5: Determination of the ideal solution and negative ideal solution:
where, J1 is a set of benefit indices, which represent the optimal
value of the jth index. J2 is a set of loss indices, which represent
the worst value of the jth index. The larger the benefit index, the more favorable
the evaluation result would be and the smaller the loss index, the more favorable
the evaluation result would be. Otherwise, the more unfavorable the estimation
result would be.
Step 6: Calculation of the Euclidean distances from the target sample
to ideal solution S* and to negative ideal solution S¯, respectively.
Step 7: Calculation of the relative similarity of each target plan to
the ideal solution.
Step 8: Sequencing of the target plans in a decreasing order of relative
SELECTION AND VALUE ASSIGNMENT OF INFLUENTIAL FACTORS
Selection of influential factors: There are many factors affecting the
design proposal of children's recreational sites. Their impacts can be huge
or small, some of them are vital, while others only affect the details. Thus,
the selected influential factors should reflect the basic characteristics of
the site. By selecting the key factors, the complexity of evaluation can be
reduced and a more scientific and feasible evaluation result will be achieved.
First, the influential factors which have caught public attention and the factors
emerging frequently in literature retrieval were sorted out. Then the experts
determined the final factors included. By doing these, the influential factors
which fully reflect the essential requirements concerning children's recreational
site would be clarified. Finally, the following seven influential factors: site
safety (x1), amenities (x2), physical space (x3),
activity representation (x4), ecological environment (x5),
quality of night scene (x6) and consideration to supervisor (x7)
Method and criteria to assign values to influential factors: The key
influential factors in optimizing children's recreational sites are qualitative,
so interval value assignment was used to ensure acquirability and validity (Table
2). Each influential factor was evaluated on a 0-10 scale (0<very poor
= 2, 2<poor = 4, 4<fair = 6, 6<good = 8, 8<excellent = 10). The
final score was the average of all scores.
Data acquisition: Four experts form Henan Agricultural University, Henan
University of Science and Technology, Henan Institute of Science and Technology
and Xinxiang Gardening Bureau scored 28 design proposals for children's recreational
site. Each proposal's final score was the average of the four scores. (Table
3) These factors were all high priority indices, which meant that the higher
the score, the better the quality of the design proposal would be. The Yaahp
6.0 software was used to calculate weights and DPS 7.5 was used to do the TOPSIS
|| The influential factors and criteria of optimizing design
proposals for children's recreational site
|| Design samples if children's recreational site and values
assigned to the influential factors
RESULTS AND DISCUSSION
Weights of influential factors: According to step 1-3, four experts
compared 7 influential factors pair wise on a 1-9 scale to calculate the weights
(Table 4). The consistency check showed 0.0915<0.1, which
conformed to the requirements.
It can be obtained from Table 4 that the decreasing order
of the weight of each influential factor is x1>x4>x2>x3>x6>x7>x5.
During the construction of children's recreational sites, site safety and amenities
are priorities. Only when the parents are assured that the amenities are safe
enough will they allow their children to use the recreational center, thereby
increasing its utilization. The recreational sites near roads or streets are
not recommended because of safety and crime problems, which will make parents
worried and children tensed (Mulvihill et al., 2000).
Amenities are the key content of the design (Giles-Corti
and Donovan, 2002). The site will be more attractive just because of these
amenities. Boys and girls have different preferences in regard to outdoor activities
and the preferences change dynamically as they get older. Thus, children's recreational
site should provide high-quality amenities for children of different age and
gender. The benefits of ecological environment are embodied in plants. Trees
and flowers are especially attractive to children. Since children's fear of
the dark can result in their reduced willingness to have night activities, good
night scene is also very important. It is also crucial to make a variety of
activities available. The research informs us that children coming from areas
with few recreational sites are less willing to participate in group activities
than those coming from areas with a great variety of recreational sites. It
is necessary to have their parents on the side of children during their outdoor
activities. However, some sites have not yet reserved space for adults to rest
or recreate, which will result in shortened duration of children's activities.
Moreover, if adults and children can participate in the activities together,
it will improve the parent-children relationships.
It should be pointed out that the weight of one influential factor represents
the relative importance of the factor; it does not mean that a low weighted
factor is unimportant. An excellent design proposal of children's recreational
site should have outstanding focuses, implemented with other auxiliary function.
Only by achieving these goals can the designed center satisfy children's recreational
Optimizing design proposals: According to Step 4-5, the ideal solution
and negative ideal solution are obtained. Ideal solution (z*) is the optimal
environmental quality of children's recreational site, with all influential
factors reaching the optimal.
|| The weights of influential factors
|| Euclidean distance Ci and sequence
And negative ideal solution (z¯) is the worst environmental quality of
children's recreational site, with all influential factors reaching the worst.
According to Step 6-7, calculate the distances from of each design proposal
to the ideal solution Z* and to negative ideal solution S*, respectively, which
are z¯ and s¯. S* is the similarity between the evaluated target to
the ideal solution. The smaller S*, the closer between the proposal and the
ideal solution, and hence the optimal the proposal would be. Calculate the similarity
Ci to the ideal solution. When Ci = 0, Si =
Z¯, which means the target plan is the worst. When Ci = 1, Si
= Z*, which means the target plan is the optimal. During the actual quality
evaluations of children's recreational sites, the possibilities of either optimal
or worst design proposals are small. Sequencing is to compare each proposal's
quality to the ideal and worst solutions, respectively and then sequence the
target plan in an increasing order of Ci. If there is a design proposal
which is closest to the ideal solution and furthest from the worst solution,
then its quality is the best among all design proposals.
According to Step 8, the final sequencing result is shown (Table
5). Ci was used to classify the design proposals for children's
recreational site into different quality grades. It can be obtained from Table
4 that proposal 27, proposal 7, proposal 13 and proposal 22 rank 1 to 4,
possessing higher comprehensive quality. The sequencing can serve as the basis
for decision making and optimization. This evaluation involved 7 key influential
factors, making the model simple and feasible. But some other indices may also
affect the design quality of children's recreational site. The interval value
assignment has certain fuzziness, though resulting in larger errors. Accordingly,
it is proposed in the study to add other evaluation indices and scoring experts
to address the above problems and thus to lower the errors.
By adopting a combination of AHP and TOPSIS, this study selected seven influential
factors: site safety, amenities physical space, activity representation, ecological
environment, quality of night scene, consideration given to supervisor, to construct
a model to evaluate and optimize the design proposals of children's recreational
AHP-TOPSIS model could differentiate among different design proposals and perform
a comprehensive, reasonable and accurate evaluation of children's recreational
sites in urban green public spaces. It is an easy and effective evaluation method.
This method can also be used to evaluate and classify other kinds of activity
sites. But it should be noted that different activity sites may have totally
different key influential indicators.