I know that a train-validation-test splits the data into:
- a training dataset - obviously my "in-sample" data
- a validation dataset
- a test data set - obviously my "out-of-sample" data
My question is: Should I refer to the validation dataset as in-sample or out-of-sample data?
If we're using the validation dataset to fine-tune the parameter values, then the model has seen this data before. So I'm thinking it is "in-sample" data. Am I right?
Thanks for your help!