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How to: Modify Column Mappings in an Accuracy Chart

You can use the Modify Mapping dialog box to change how columns in the data mining model are mapped to columns in the testing data set.

When you specify an external data source to use in measuring mining model accuracy, SQL Server 2008 Analysis Services (SSAS) automatically maps some columns to the columns in the mining model. You can change these mappings, delete mappings, or create new mappings for existing columns. However, you cannot add new columns or map columns in a different data source view. The data source view that you select must contain all the columns that you need for the prediction query.

You are only required to map columns if you are using an external data source to test the mining model. If you select the options Use mining model test cases or Use mining structure test cases when you choose your data, the correct columns of data are provided automatically.

To modify column mappings for an accuracy chart

  1. In Data Mining Designer, double-click the structure that contains themodels you want to chart.

  2. Select the Mining Accuracy Chart tab.

  3. Click the Input Selection tab.

  4. In Select data set to be used for Accuracy Chart, select the option Specify a different data set.

  5. Click the browse button (…) to open a dialog box and build the definition of the external data source.

  6. In the Specify Column Mapping dialog box, click Select Case Table.

  7. In the Select Table dialog box, Select a data source view from the list, and select the table that contains the case data. Click OK.

  8. If the tables you need are not available, close the dialog box and create a new data source view that contains the table. For information about how to create a data source view, see Defining a Data Source View (Analysis Services).

  9. If the mining model contains a nested table, click Select Nested Table, and select the nested table from the list of tables in the data source view. Click OK.

  10. Select the join line of the mapping you want to modify, and select Modify Connections.

    The Modify Mapping dialog box opens. In the table in this dialog box, Mining Structure Column lists each column that the selected mining structure contains, and Table Column lists the columns from input tables that are mapped to columns in the mining structure.

  11. Under Table Column, select the row that corresponds to the row under Mining Structure Column for which you want to modify a relationship. Select a new column from the list, or select the blank entry from the list to delete the column.

  12. Click OK.

    The new column mappings are displayed in the Specify Column Mapping dialog box. You can remove a mapping by selecting the line between the columns and pressing the DELETE key. You can create a new connection by selecting a column in the Mining Structure table and dragging it to the corresponding column in the SelectInput Table(s) table.