Optimizing architectures of recurrent neural networks for improving the accuracy of time series forecasts

Содержание

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Outline The main purpose and subtask of research Literature review results

Outline

The main purpose and subtask of research
Literature review results
Comparison of

different models on transaction data
Further work plan

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The purpose and subtasks The main purpose: Optimizing RNN parameters to

The purpose and subtasks

The main purpose:
Optimizing RNN parameters to improve the

accuracy of forecasting

Subtasks:
Review current approaches to financial time series forecasting
Compare models and test accuracy
Optimizing parameters of RNN

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Literature review Common approaches for analysing financial time series: 1) Classic

Literature review

Common approaches for analysing financial time series:

1) Classic

statistical methods
Regression models
Autoregressive integrated moving average models
Exponential smoothing
Generalized autoregressive conditionally heteroskedastic methods
2) Artificial neural networks

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Literature review Specific features of statistical approaches: Demonstrate high accuracy result

Literature review

Specific features of statistical approaches:

Demonstrate high accuracy result

especially when time series have pattern as trend and/or seasonality
Better work for short-term forecasting
Sensitive to outliers
Optimization of models parameters is quite simple
Do not require much computational power for evaluation

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Literature review Specific features of Recurrent Neural Networks: Able to approximate

Literature review

Specific features of Recurrent Neural Networks:

Able to approximate

complex relationships in time series
Able to forecast for long-term
Optimization of model parameters is quite difficult
Require much computational power for evaluation
Robust to outliers with appropriate parameters' optimization

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Literature review Long Short-Term Memory extends the RNN architecture with a

Literature review

Long Short-Term Memory extends the RNN architecture with a

standalone memory

Fig. 1 – Structure of LSTM memory block

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Literature review Feature based approach to model selection 8/17

Literature review

Feature based approach to model selection

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Literature review Algorithm of model selection 9/17

Literature review

Algorithm of model selection

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Model comparison Training details: Linear Regression - 91 parameters including bias

Model comparison

Training details:

Linear Regression
- 91 parameters including bias
Holt-Winters Model
- alpha =

0.55, beta = 0.01, gamma = 0.85
Recurrent Neural Network
- LSTM with 1 layer, with 512 cells.
- The input shape was defined as 1 time series step with 90 features.
- Stochastic gradient descent with fixed learning rate of 0.01 was used as optimizer, loss-function – Mean Squared Error.

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Model comparison Data description Fig. 1 - Daily transaction amount, millions

Model comparison

Data description

Fig. 1 - Daily transaction amount, millions of

rub
(from Nov. 2013 to Apr. 2016 )

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Model comparison Results Fig. 2 – Linear regression 12/17

Model comparison

Results

Fig. 2 – Linear regression

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Model comparison Results Fig. 3 – Holt-Winters Model 13/17

Model comparison

Results

Fig. 3 – Holt-Winters Model

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Model comparison Results Fig. 4 – Recurrent Neural Network 14/17

Model comparison

Results

Fig. 4 – Recurrent Neural Network

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Model comparison Results Table 1 – Performance of models on test data set 15/17

Model comparison

Results

Table 1 – Performance of models on test data

set

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Outputs Findings: Recurrent Neural Network can outperform the other classical statistical

Outputs

Findings:

Recurrent Neural Network can outperform the other classical statistical models in

predictive accuracy
More advanced hyper-parameters selection scheme might be embedded in the system to further optimization the learning framework
Selection of model highly depends on time series features

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