# Mining Model Content for Logistic Regression Models (Analysis Services - Data Mining)

**SQL Server 2008 R2**

This topic describes mining model content that is specific to models that use the Microsoft Logistic Regression algorithm. For an explanation of how to interpret statistics and structure shared by all model types, and general definitions of terms related to mining model content, see Mining Model Content (Analysis Services - Data Mining).

A logistic regression model is created by using the Microsoft Neural Network algorithm with parameters that constrain the model to eliminate the hidden node. Therefore, the overall structure of a logistic regression model is almost identical to that of a neural network: each model has a single parent node that represents the model and its metadata, and a special marginal statistics node (NODE_TYPE = 24) that provides descriptive statistics about the inputs used in the model.

Additionally, the model contains a subnetwork (NODE_TYPE = 17) for each predictable attribute. Just like in a neural network model, each subnetwork always contains two branches: one for the input layer, and another branch that contains the hidden layer (NODE_TYPE = 19) and the output layer (NODE_TYPE = 20) for the network. The same subnetwork may be used for multiple attributes if they are specified as predict-only. Predictable attributes that are also inputs may not appear in the same subnetwork.

However, in a logistic regression model, the node that represents the hidden layer is empty, and has no children. Therefore the model contains nodes that represent individual outputs (NODE_TYPE = 23) and individual inputs (NODE_TYPE = 21) but no individual hidden nodes.

By default, a logistic regression model is displayed in the Microsoft Neural Network Viewer. With this custom viewer, you can filter on input attributes and their values, and graphically see how they affect the outputs. The tooltips in the viewer show you the probability and lift associated with each pair of inputs and output values. For more information, see Viewing a Mining Model with the Microsoft Neural Network Viewer.

To explore the structure of the inputs and subnetworks, and to see detailed statistics, you can use the Microsoft Generic Content Tree viewer. You can click on any node to expand it and see the child nodes, or view the weights and other statistics contained in the node.

This section provides detail and examples only for those columns in the mining model content that have particular relevance for logistic regression. The model content is almost identical to that of a neural network model, but descriptions that apply to neural network models may be repeated in this table for convenience.

For information about general-purpose columns in the schema rowset, such as MODEL_CATALOG and MODEL_NAME, that are not described here, or for explanations of mining model terminology, see Mining Model Content (Analysis Services - Data Mining).

The naming of the nodes in a logistic regression model provides additional information about the relationships between nodes in the model. The following table shows the conventions for the IDs that are assigned to nodes in each layer.

Node Type | Convention for node ID |
---|---|

Model root (1) | 00000000000000000. |

Marginal statistics node (24) | 10000000000000000 |

Input layer (18) | 30000000000000000 |

Input node (21) | Starts at 60000000000000000 |

Subnetwork (17) | 20000000000000000 |

Hidden layer (19) | 40000000000000000 |

Output layer (20) | 50000000000000000 |

Output node (23) | Starts at 80000000000000000 |

You can use these IDs to determine how output attributes are related to specific input layer attributes, by viewing the NODE_DISTRIBUTION table of the output node. Each row in that table contains an ID that points back to a specific input attribute node. The NODE_DISTRIBUTION table also contains the coefficient for that input-output pair.