Greetings
from NeuroDimension!
The World Leader in Neural Network Software
This issue of the NeuroDimension
newsletter highlights the latest developments at NeuroDimension, as well as
providing insights on how and when to use neural networks.
In this issue you’ll find:
What’s New
and News?
* TradingSolutions Real-Time
Beta Available
Note: You are
receiving this newsletter because you requested to stay informed concerning new
developments at NeuroDimension. If you would like to stop receiving these
newsletters, please see the bottom of this newsletter for removal instructions.
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
NeuroDimension will soon be releasing TradingSolutions
Real-Time and TradingSolutions End-of-Day v2.1. To ensure quality
standards, a beta release of both versions is being made available to current
licensed users of TradingSolutions in advance of its full release.
TradingSolutions v2.1 will be available in both Real-Time and End-of-Day versions and will
introduce many new
features and enhancements, including: streaming data support, programmable
alerts, eSignal data support, and asynchronous processing. TradingSolutions
Real-Time will be priced at $1995. Upgrading from TradingSolutions v2.0 to
TradingSolutions End-of-Day v2.1 will be free. Upgrading to TradingSolutions
Real-Time will be $1000.
Use of the beta is free. Availability is currently limited to licensed TradingSolutions users.
The beta version includes all of the features being added in v2.1, including
those found only in the real time version. For more information about this
beta, log into the Licensed User Center on the TradingSolutions web site or
contact us at info@tradingsolutions.com
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
Designing Neural Networks
Neural
networks are nonlinear models. As such, linear statistical methods such as
correlation analysis may not provide a complete picture when analyzing
input-output relationships.
Correlation
Analysis
When
trying to determine which inputs will be “good” for predicting an output, in
linear methods you would use correlation analysis. The higher the correlation
with the output, the better the input predicts the output. Specifically, if an
input value moves in some direction, highly correlated output values will move
by a proportional amount. Correlation analysis, however, only measures linear relationships.
Good
Inputs With Low Correlation
Indicators
and state-related variables are a good example of inputs that may be
nonlinearly related to the output. They can take the form of “if X = true, do
this, otherwise do that”, which is a non-linear relationship. This type of
input can be very important to the solution and yet may have a very low
correlation.
Another
example is as follows: assume you have a function y = x1 * x2 where both x1 and
x2 are variables. This is not a linear function. If x1 varies from -1 to 1 and
x2 varies from 0 to 1, then x1 will have a reasonably high correlation with y
(high x1 generally means high y, low x1 generally means low y), but x2 will
have a very low correlation with y because x1 switches the sign of y independent
of the value of x2. Thus, a large x2 sometimes means a large positive y and
sometimes means a large negative y. A simple 1 hidden layer MLP can easily
solve this nonlinear function, but a linear system could not – and in addition,
the correlation analysis would be deceptive as to which variables are important
to the solution.
Use
Correlation Analysis Wisely
In neural
networks, we recommend you use correlation analysis only as an initial guess as
to which variables may be important. Values with high correlation to the output
have a good possibility of being useful inputs. However, values with low
correlation may still be very important components in nonlinear relationships.
Sensitivity
analysis is a preferred way of detecting the significance of non-linear inputs.
For more information about sensitivity analysis, see the previous newsletters.
A list of previous newsletters by topic is available at: http://www.neurosolutions.com/newsletters_topic.html
=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=~=
We appreciate your feedback! Please send us your comments or
suggestions concerning this newsletter, our web site, or part of the
NeuroDimension product line. Write to us at: feedback@nd.com
Have questions about NeuroDimension products or training
services? Send your questions to: info@nd.com
Some mail readers may display an attachment at the bottom of
this newsletter. This is typically caused when the mail reader is set to
display text only. The original, formatted version is sometimes included as an
attachment.
This issue and previous issues of this newsletter are
available on the NeuroDimension web site at: http://www.neurosolutions.com/newsletters.html
If you would prefer not to receive these newsletters or
subsequent product updates from NeuroDimension, please reply to this letter
with the subject heading changed to the word REMOVE.
Thank you again for your support of NeuroDimension products!