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Choose and Map Model Testing Data

To create an accuracy chart in Analysis Services, you must choose the data that will be used to test the model, and map the data to the model.

By default, Analysis Services will use the mining model testing data, provided that you created a holdout data set when you built the mining structure. Creating a holdout test set is the easiest way to test models that are based on the same mining structure, because the column names and data types will always match the model, and you can be reasonably assured that the distribution of the data is similar. Also, the designer will automatically create the relationships between the input and model columns.

Alternatively, you can specify an external source of data. For external data, there are some additional requirements:

  • The external data set must be defined as a data source view in an instance of Analysis Services. 

  • The external data set must at least contain one column that can be mapped to the predictable column in the mining model. You can choose to ignore some columns.

  • 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.

  • If the external column names exactly match those in the model, the designer will map them for you. If the mappings are wrong, you can change them, or delete and create new mappings for existing columns.

  • If you use an external data source, you can apply filters to restrict the testing data to a relevant subset of cases.

  • Even when you use the holdout test set, you should be aware that filters can cause differences between the testing data associated with a mining structure and the mining model test cases.

This topic describes how to choose and map the testing data:

Select input tables to test the accuracy of a mining model

Map model columns to the columns in the testing data

Change the way that columns in the testing data are mapped to the model

To select input tables to test the accuracy of a mining model

  1. In Data Mining Designer in SQL Server Data Tools (SSDT), double-click the mining structure that contains the models you want to chart.

  2. Select the Mining Accuracy Chart tab.

  3. On the Input Selection Tab of the Mining Accuracy Chart view, select one of the following options:

    Use mining model test cases

    Use mining structure test cases

    Specify a different data set

  4. If you selected Specify a different data set, optionally click Open Filter Editor to create filter conditions on the input data set. Click OK.

  5. Click the Lift Chart tab or the Classification Matrix tab to automatically build the chart by using the testing data you specified.

To map model columns to the columns in the testing data

  1. Double-click the mining structure that contains the models you want to chart, to open the structure and models in Data Mining Designer.

  2. Select the Mining Accuracy Chart tab, and then select the Input Selection tab.

  3. In the Input Selection tab, under Select data set to be used for Accuracy Chart, select Specify a different data set.

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

  5. In the Select Mining Structure dialog box, select the mining structure that contains the models you want to work with, and then click OK.

  6. On the Select Input Table(s) table of the Mining Accuracy Chart tab, click Select Case Table to open the Select Table dialog box.

  7. In the Select Table dialog box, select a data source from the Data Source list. Choose a table that contains the data that you want to use in the prediction queries to determine the accuracy of the models.

  8. In the Table/View Name box, select the table that contains the data that you want to use to test the models.

  9. Edit the mappings, if necessary. Columns in the mining structure are automatically mapped to the columns with the same name in the input table. To manually create mappings, click a column in the Select Input Table(s) table and drag it onto the corresponding column in the Mining Structure table. To delete a mapping, click the line that links the column in the Mining Structure table to the mapped column in the Select Input Table(s) table, and then press DELETE.

  10. Click OK.

To modify the way input data is mapped to the model

  1. In Data Mining Designer, double-click the structure that contains the models 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 Select Input Table(s) table.

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