Tourism Demand Forecasting Model Using Neural Network

International Journal of Computer Science & Information Technology (IJCSIT) Vol 9, No 2, April 2017
DOI:10.5121/ijcsit.2017.9202 19
TOURISM DEMAND FORECASTING MODEL USING
NEURAL NETWORK
Han-Chen Huang and Cheng-I Hou
Department of Tourism and M.I.C.E., Chung Hua University, Taiwan
ABSTRACT
Travel agencies should be able to judge the market demand for tourism to develop sales plans accordingly.
However, many travel agencies lack the ability to judge the market demand for tourism, and thus make
risky business decisions. Based on the above, this study applied the Artificial Neural Network combined
with the Genetic Algorithm (GA) to establish a prediction model of air ticket sales revenue. GA was used to
determine the optimum number of input and hidden nodes of a feedforward neural network. The empirical
results suggested that the mean absolute relative error(MARE) of the proposed hybrid model’s predicted
value of air ticket sales revenue and the actual value was 10.51%and the correlation coefficient was 0.913.
The proposed model had good predictive capability and could provide travel agency operators with
reliable and highly efficient analysis data.
KEYWORDS
Artificial neural network;Genetic algorithm;Air ticket sales;Prediction model
1. INTRODUCTION
There are nearly 3,500 travel agencies competing in the overseas tourism market in Taiwan, with
a value of about USD21billion per year [1]. In a competitive environment, travel agencies must
be able to accurately predict the market demand to make the right operational decisions. However,
tourism is not an essentialcomponent of people’s lives, and tourism can be directly affected by
economic downturns. Travel agency operators should have good predictive capability formarket
demand and excellent financial management capability; otherwise, it will bedifficultto survive in
a competitive market [2].
Among the numerous businesses of travel agencies, air ticket salesarean extremely important
source of revenue. If atravel agency can accurately predict the market demand for air tickets, it
can purchase a sufficient amount of air ticketsat alow cost to have the opportunity to get higher
sales profits. In addition, it can reduce the cost accumulation during the purchase process or order
loss due to lack of air tickets[3,4].
Studies inthe past have developed many sales prediction models, such as qualitative methods(the
Delphi method, market research, and the group opinion method), the sequence analysis method
(exponential smoothing, autoregressive models, moving average models, etc.) andeconometric
methods (discussing the relationship with external economic variables and using statistical
theoretical method to measure or test the relationships in between some variables to provide the
basis for analysis). However, these models have a number of limitations[5]. In recent years, the
prevalent prediction method has beenartificial intelligence. Among the various types of artificial
intelligence prediction models, neural networkshavebeen confirmed as a very effective tool[6].
Therefore, this study applied anArtificial Neural Network (ANN) combined with the Genetic
Algorithm(GA) to establish a prediction model forair ticket sales revenue. The findings of this
study couldprovide the industry with a more reliable and efficient reference in practical operation.

20
2. LITERATURE REVIEW
2.1. Travel Agencies
Travel agenciesare the mediators of tourism product suppliers and customers, as they are
responsible for planning and making arrangements for tours in order to win profits[2]. In
accordance with Taiwan’s Statute for the Development of Tourism[7] Article 2 states that a travel
enterprise is: “also referred to as travel agency, a profit-taking enterprise licensed by the central
administrative authority to provide tourists with arranged travel schedules, board and lodging,
tour guides, and to purchase transportation tickets and apply for travel documents and visas on
tourists’ behalf, as well as to provide related services for remuneration.”
There are nearly3,500 travel agencies competing in the overseas tourism market in Taiwan, with
a value of about USD21 billion per year[1]. In such a competitive environment, travel agencies
must be able to more efficiently and accurately predict market demand to make the right
operational decisions. If a travel agency can understand the market demand earlier than its
competitors, purchase products, mobilize manpower and adjust business operational directions in
advance, it can surely win in a fiercely competitive environment.
2.2. Prediction Methods
Stynes[8] categorized prediction methods into four types: 1) the Delphi technique; 2) time series
or trend extension models; 3) structural models; and 4) system or simulation models. The
commonly-used prediction methods proposed in other related studies [9-16] include trend
analysis, cause analysis, judgment analysis, survey analysis, and artificial neural networks,etc.
2.2.1. Trend Analysis
The trend analysis method is used to predict the trend changes in future sales of an enterprise
according to the historical sales data by using certain calculation methods. Such a method is
suitable for enterprises with relatively stable product sales. It mainly includes the simple moving
average method, the moving average method, the weighted moving average method, the
exponential smoothing method and the seasonal prediction method.
2.2.2. Cause Analysis
Various factors in economic activities are often interrelated, mutually influential,and form a
certain corresponding relationship among each other. Product sales in general are affected by
various factors. The cause analysis method is used to find the function relationship of various
related factors that may affect product sales and sales volume, as well as to predict future sales
according to such a causality relationship. Such a method often requires the establishment of
prediction mathematical model, and thus it is often known as the regression analysis method. It
commonly includes simple regression analysis and multiple regression analysis.
2.2.3. Judgment Analysis
As a qualitative analysis method, judgment analysis is mainly based on the analysis of future
market changes according to the experience of management personnel, personnel with sales
experience, or other experts, in order to determine the sales trends of certain products in a certain
period of time
.

21
2.2.4. Survey Analysis
The survey analysis method is used to predict the sales trends of the product of an enterprise by
investigating the demand and supply of a certain product and the consumption orientation of
consumers. The survey contents may include product surveys, customer surveys, surveys on
economic development trends and industry surveys, etc.
2.2.5Artificial Neural Network
An artificial neural network (ANN) is a mathematical model imitating the structure and function
of a biological neural network. The neural network performs calculations using a large amount of
artificial neurons. In most cases, ANN can change the internal structure according to external
information as an adaptive system. ANNs are a modeling tool for non-linear statistical data, and
they are commonly used for the modeling of complex relationships between input and output or
data exploration [17].
ANN construction is generated by the inspiration of biological neural networks. ANN can have
human-like simple determination capability and judgment, which is advantageous to formal logic
reasoning.A common multilayer feedforward network consists of three parts (Figure 1)[18-20]:
• The input layer, in which numerous neurons receive a large amount of input
information.
• The output layer, in which information is transmitted and analyzed in neuron links to
form the output results.
• The hidden layer, which is a layer with numerous neurons and links in between the
input and the output layers. It can consist of multiple layers but is customarily one
layer only. There is no recognized number of neurons in the hidden layer; however,
when the number of neurons is larger, the non-linearity will be more significant and
the robustness of the neural network will be more significant.
Figure 1. BPNN network architecture[18-20]
The Back Propagation Neural Network (BPNN) is the most representative and commonly used
ANN[18]. BPNN applies the steepest descent method to adjust the parameters of the network and

22
obtain a more accurate solution by iteration computation. BPNN has high-speed computing
power, a fast recall speed, high learning accuracy, and fault tolerance, and thus it has been widely
applied in different fields[18-20].
3. RESEARCH METHOD
3.1. Back Propagation Neural Network
BPNN is a supervised learning algorithm consisting of ANNs.A BPNN is the combination of
multilayer perceptrons (MLP) and error back propagation (EBP). The computation process can be
divided into the learning process and the recall process[21].
3.1.1. Learning process
Step1: Set the network architecture parameters and learning parameters
Step2: Randomly generate the weight matrix and bias vector initial value
Step 3: Input the training examples, including the input values (X1,X2,X3) and target output
values (T1,T2,T3)
Step4: Compute and infer the output values (Y1,Y2,Y3)
(1) Hidden layer (H1,H2,H3)(Eq.1 and 2)
∑ −=
i
kiikk xWnet θ (1)
)exp(1
1
k
k
net
H
−+
= (2)
(2) Output layer(Y1,Y2,Y3) (Eq.3 and 4)
∑ −=
ki
jkkjj hWnet θ (3)
)exp(1
1
j
j
net
Y
−+
= (4)
Step5: Compute the gap δ(Eq.5 and 6)
(1)Hidden layer
)1()( jk
j
kjjk HhW −⋅⋅⋅= ∑δδ (5)
(2) Output layer
)1()( jjjjj YYYT −⋅⋅−=δ (6)
Step6: Compute weight revision and bias revision (Eq.7~10)
(1) Hidden layer
)1()( −∆⋅+=∆ nWxnW ikikjk αηδ (7)

23
)1()( −∆⋅+−=∆ nn kjkk θαηδθ (8)
(2) Output layer
)1()( −∆⋅+=∆ nWHnW kjkjkj αηδ (9)
)1()( −∆⋅+−=∆ nn jjj θαηδθ (10)
Step7: Update the weight and bias(Eq.11~14)
(1) Hidden layer
jkjkjk WWW ∆+= (11)
kkk θθθ ∆+= (12)
(2) Output layer
kjkjkj WWW ∆+= (13)
jjj θθθ ∆+= (14)
Step8: Repeat Step 3- Step 7 until convergence (no significant change in error or
implementation of certain times of learning cycles).
3.1.2. Recall process
Step 1: Set network parameters
Step 2: Read in theweight matrix and bias vector
Step 3: Input the unknown data vector(X1,X2,X3)
Step 4: Compute and infer the output vector(y1,y2,y3)
(1) Hidden layer output values (H1,H2,H3) (Eq.15 and 16)
∑ −=
i
kiikk XWnet θ (15)
)exp(1
1
k
k
net
H
−+
= (16)
(2)Compute and infer the output values (Y1,Y2,Y3) (Eq.17 and 18)
∑ −=
k
jkkjj HWnet θ (17)
)exp(1
1
j
j
net
Y
−+
= (18)
3.2. Forecast Model Variables
According to the relevant literature [13-16,22-26], this study used theNTD/USD exchange rate,
the number of people traveling abroad from Taiwan each month, the international oil price, the

24
Taiwan stock market weighted index, Taiwan’s monthly monitor indicator, Taiwan’s monthly
composite leading index, Taiwan’s monthly composite coincident index, and W travel
agency’s monthly air ticket sales(T-1～T-18)( Table 1) as the input variablesto predict W travel
agency’s air ticket sales revenue in Month T. The selected data were the monthly data of the
period from January 2003 to December 2015. This study randomly selected70%as the training
Data,15% as the cross validation data, and 15% as the testing data.GA improves the performance
of ANNs by selecting the optimum input features of the neural network. This study used different
operators for selection and crossover operations (Table 2)[26-30].
Table1. Forecast model variables
Variable Unit
Input
NTD/USD exchange rate (T-1 month) NTD/USD
Number of people traveling abroad from Taiwan each month
(T-1 month)
Number of people
International oil price (T-1 month) USD/Barrel
Taiwan stock market weighted index (T-1 month) Point
Taiwan’s monthly monitor indicator (T-1 month) Score
Taiwan’s monthly composite leading index (T-1 month) Point
Taiwan’s monthly composite coincident index (T-1 month) Point
W Travel Agency’s air ticket sales revenue(T-1 month to
T-18 month)
NTD
Output Air ticket sales revenue (T month) NTD
Table 2. Description of different operators for select and crossover operations in GA[26-30]
Operation Operator Description
Select
Best Selects the best chromosome.
Random Randomly selects a chromosome from the population.
Tournament
The winner of each tournament (the one with the best
fitness) is selected for crossover.
Top percent (15)
Randomly selects a chromosome from the top 15 percent
of the population.
Roulette
The chance of a chromosome getting selected is
proportional to its fitness.
Crossover
Arithmetic
Linearly combines two parent chromosome vectors to
produce two new offspring.
Heuristic
Use the fitness values of the two parent chromosomes to
determine the direction of the search.
Uniform
Decides (with some probability – known as the mixing
ratio) which parent will contribute each of the gene values
in the offspring chromosomes.
One point
Randomly selects a crossover point within a chromosome,
interchanges the two parent chromosomes at this point to
produce two new offspring.
Two point
Randomly selects two crossover points within a
chromosome, interchanges the two parent chromosomes
between these points to produce two new offspring.

25
3.3. Architecture Design and Model Training
ANN’s input activation function uses the hyperbolic tangent, the output error function uses the
sum-of-squares andthe output activation function uses logistic. GA improves the performance of
ANNs by selecting the optimum hidden nodes of the neural network. This study used different
operators for selection and crossover operations (Table 2)[26-30].
Training Algorithm: Quick Propagation Algorithm, Training Algorithm’s Parameters is Quick
Propagation Coefficient = 1.75, Learning Rate=0.1. The overtraining control and weights
randomization methodwere used to increase the model accuracy (Figure 2).
4. EMPIRICAL RESULTS
The correlation (r) and Mean Absolute Relative Error (MARE) were adopted as indicators for
evaluating the model.
• Correlation (r): As r approaches 1, the model predicted value and actual value correlation
level becomes higher.
• MARE(Eq. 19): The smaller the value, the smaller the error between the forecast value
and the actual value:
%100
'1
1
⋅
−
= ∑
n
i
ii
Y
YY
n
MARE (19)
where n is the number of the forecasting periods, Yi is the actual value for the i period, and
iY' is the forecast value for the i period.
Figure 2. Training options
The optimal network architecture is 12-142-1（Figure 3 and Table 3）. The input layer had 12
neurons, the hidden layer had 142 neurons, and the output layer had one neuron. The actual value
and model output value distribution are shown in figure 4. It can be learnt from the figure that the
model output value was largely distributed along both sides of the diagonal line
(Output/Target=1), indicating the model had good predictive capability. The trends of the actual
value and model output valueare shown in Figure 5. It can be learnt from the figure that the
established air ticket sales revenueprediction modelhad a good capability to reflect the change in

26
sales of air tickets. The prediction results of the model are shown in Table 4. The mean absolute
relative error (MARE) was10.51%, the correlation coefficient was 0.913, and the model had the
capability of accurately predicting the air ticket sales revenue.
Figure 3. Best network architecture search results
Table 3. Performance of the Proposed Model in Prediction
Select operator Crossover operator Number of inputs Number of hidden nodes MARE Correlation
Best
Arithmetic 10 24 0.1113 0.913
Heuristic 7 22 0.1301 0.876
Uniform 11 53 0.1471 0.919
One point 9 90 0.1149 0.876
Two point 5 75 0.1281 0.900
Random
Arithmetic 4 127 0.1215 0.916
Heuristic 7 86 0.1426 0.923
Uniform 4 8 0.1457 0.928
One point 8 127 0.1270 0.898
Two point 7 142 0.1051 0.913
Tournament
Arithmetic 5 54 0.1284 0.876
Heuristic 8 136 0.1337 0.890
Uniform 13 149 0.1251 0.897
One point 13 34 0.1539 0.925
Two point 10 72 0.1607 0.936
Top percent (15)
Arithmetic 4 17 0.1406 0.920
Heuristic 9 20 0.1447 0.923
Uniform 11 65 0.1296 0.923
One point 12 64 0.1647 0.915
Two point 7 24 0.1093 0.934
Roulette
Arithmetic 4 23 0.1532 0.916
heuristic 13 58 0.1421 0.878
Uniform 6 5 0.1136 0.875
One point 12 143 0.1211 0.918
Two point 5 104 0.1451 0.913

27
Figure 4. Scatter plot of actual value and model output value
Figure 5. Time series of actual vs. predicted
5. CONCLUSION
This study used theBack Propagation Neural Network and Genetic algorithm (GA) to establish a
travel agency air ticket sales revenue prediction model. GA was used to determine the optimum
number of input and hidden nodes of a feedforward neural network. The empirical results
suggested that the proposed prediction modelhad the capability to accurately predict air ticket
sales revenue and reflect the change in air ticket sales. The MARE of the model was only 10.51%,
and the correlation coefficient was up to 0.913., whenusing the proposed prediction model,travel
agency operators can predict the future demand for air tickets and purchase sufficient air tickets at
a lower cost to win more profits. It could reduce the loss caused by excessive purchaseor
customer loss caused by lack of stock.

28
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