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output changes is directly related to the performance of neural network prediction. The
number of tourist is restricted by many factors, for example, geography, environment,
culture, government policy, etc. If all these factors are considered, it will bring a lot of
inconvenience to predict. Tourists quantity every five years as the neural network input
variables is the innovation of the article, so Input samples can be determined by the
input variable. We can select the sixth year number of tourists after every five years as
the neural network output variable.
2.2 Input Samples Pretreatment
Since the implicit function of RBF neural network is Gaussian function, which general
requires for input value between 0 and 1, do normalize on the number of Hainan
province tourists from 1988 to 2008. Normalization is basically the same way to
statistical data normalization, generally using the following form:
X
X
__
X
=
min
(5)
X
X
max
min
Where X is the actual value of sample;
X takes a large value, ensuring forecast
year is less than the value; mi X takes a sample of data is less than the minimum value
to ensure normalized value is not close to 0. After the pretreatment of data completes
the training, do process data (inverse transform) to get the actual value.
max
Table 1. The actual number of visitors of Hainan Province in 1988 to 2008
Years
1988
1989
1990
1991
1992
1993
1994
Tourists quantity(million)
118.54
88.05
113.46
140.61
247.37
274.41
289.60
Year
1995
1996
1997
1998
1999
2000
2001
Tourists quantity(million)
361.01
485.82
791.00
855.97
929.07
1000.76
1124.76
Year
2002
2003
2004
2005
2006
2007
2008
Tourists quantity(million) 1254.54 1234.11
1402.88
1516.47
1605.02
1873.78
2060.00
Note: Table 1 Data from the Hainan Provincial Bureau of Statistics.
2.3 Determining Training Samples and Test Samples
From the above we can determine the number of input neuron of RBF neural network is
5, and the number of output neurons is 1. Treating the samples as follows [6]: Input
neuron P=[p(t-5),p(t-4),p(t-3),p(t-2),p(t-1)]; Output neurons T=[p'(t)]. Where, t =
1993, 1994 ... ... 2008, P (t) denote the normalized number of tourism at t year. In this
method, we can obtain the training samples and test samples.
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