Each variable in a data set has a name and a range of Excel cells
associated with it. Each column within the range contains data for a
different variable. A data set can include multiple blocks of cells,
allowing you to put data on different sheets in the same workbook.
When you are defining a data set, NeuralTools attempts to identify
the variables in a block of cells surrounding the current selection in
Excel. This makes it quick and easy to set up a data set with variable
names in the top row and variables laid out by column.
In NeuralTools, variables can be independent or dependent and
numeric or categorical (for example Yes or No, or Red, Green or Blue.)
The Data Set Manager attempts to identify the type of each variable in
your data set, but you can override this with your own selections.
A single column in an Excel 2003 or earlier worksheet can hold up to
65,536 data points for a variable. If your variables have more values
than this and you choose not to adopt Excel 2007, NeuralTools allows
multiple cell ranges to be assigned to a single data set. In other
words, you can "repeat" a data set across multiple sheets, assigning
the same columns in different worksheets to hold all the values for a
data set.
Training a Neural Network
After you have defined a data set that contains cases with known
historical values, you can train a neural network using that data.
There are different options that determine the type of network that
will be generated by NeuralTools. Depending on the nature of your
data, different network options will generate better performing
trained networks (i.e. networks that do a better job predicting
answers). The testing process – done following training – gives
precise measurements of how well your trained network does at
predicting output values.