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Old 01-21-2013, 08:03 AM
curiosity curiosity is offline
Junior Member
Join Date: Jan 2013
Posts: 4
Default Re: When to use normalization?

One important precaution when normalizing the data: if you are using something like validataion to estimate your test error, always normalize only the training data, and use the resulting normalization parameters to rescale the validation data. If you do not follow this strict prescription, then your validation estimate will not be legitimate.
Thanks for the quick reply magdon. However, I didn't get this. What is the difference between normalizing and rescaling in this case? For the general case can you also please describe whether I need to also normalize my test data when evaluating the final model? Or in other words how should I evaluate the final model if I have used normalization during training? An example would be very appreciated...
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