By default the last 1/4 of the interval is used for validation. The help below defines further how to specify a user defined interval for validatoin. Survival Node Train Properties: Survival Validation The Survival Validation section of the Survival node Properties panel provides the following settings for configuring the validation of your Survival model: Survival Validation Method – Use the Survival Validation Method property to specify how the validation holdout sample is generated. By default, the training, validation and test data sets that are passed to the Survival node are split into two time intervals. The first 75% of the interval is set aside as training data, for model creation. The remaining portion of the interval is set aside for survival model validation, or scoring. When the default survival validation method is selected, the entire scoring interval is used for validation calculations. However, you can choose to create a user-specified time interval if you desire. When you select user-specified time intervals, you can specify a specific hypothetical scoring date as well as the interval length. Scoring Time – When you select User Specified as the value for your Survival Validation Method setting, you can use the Scoring Time property to specify a hypothetical scoring date. The hypothetical scoring date will divide the data into the two subsets of data. Select the button to the right of the Scoring Time property to open a table that you use to specify the date value for scoring. The Scoring Time date value that you specify must fall between your defined start date and censor date. Interval Length – When you select User Specified as the value for your Survival Validation Method, the Interval Length property specifies the length of the time interval used to perform survival validation. The interval will begin with the hypothetical scoring date that you specified in the Scoring Time property setting, and then extend the specified number of time intervals forward. If the Time Unit property is set to Day and the Interval Length property is set to 15, your scoring interval is the 15 days that follow the hypothetical scoring date.
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