This is hypothetical and I would like to hear what people do when the get to the test set and realize they've overfit. Of course, preventing overfitting in the first place is ideal.
You're working on a prediction problem and you split your data into a Train, Validation, and Training set. You're MSE on Validation is within a reasonable value of you're train MSE. However, when you get to your test set, the MSE is very poor. What do you do?
Some Ideas I have
- Use a less complex model or regularize more
- Make sure there are no common issues: data leakage, forward looking bias, etc.
- Get more data
What else?
Say you still do all of this and the model still seems to be overfitting.