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A subset of Source Dataset which is used to train Model parametersmodel parameters.

The discrepancy between model values and Training dataset values can be low but it does not mean that predicting accuracy of the model on the data outside the Training dataset will be the same low. 

This may happen because the model is not unique and a given model realization may not be the best predictor.

In order to assess predictability of the model it should bee validated on the data outside the Training dataset, which is called Validation dataset.

See also

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Natural Science / System / Model 

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