MullOverThing

Useful tips for everyday

# What is validation and training loss?

## What is validation and training loss?

One of the most widely used metrics combinations is training loss + validation loss over time. The training loss indicates how well the model is fitting the training data, while the validation loss indicates how well the model fits new data.

Should validation loss be lower than training?

If your training loss is much lower than validation loss then this means the network might be overfitting . Solutions to this are to decrease your network size, or to increase dropout. For example you could try dropout of 0.5 and so on. If your training/validation loss are about equal then your model is underfitting.

Why my validation loss is lower than training loss?

Reason #2: Training loss is measured during each epoch while validation loss is measured after each epoch. The second reason you may see validation loss lower than training loss is due to how the loss value are measured and reported: Training loss is measured during each epoch.

### What does validation loss mean?

“Validation loss” is the loss calculated on the validation set, when the data is split to train / validation / test sets using cross-validation.

Is validation loss used in training?

Validation loss is the same metric as training loss, but it is not used to update the weights.

How is validation loss calculated?

In my code, 80 datasets are used for training and 20 datasets are used for validation. In my code, the neural network is prediction this formula: y =2X^3 + 7X^2 – 8*X + 120 It is easy to compute so I use this for learning how to build neural network through PyTorch. The validation loss is a flat line.

## What is training and validation accuracy?

In other words, the test (or testing) accuracy often refers to the validation accuracy, that is, the accuracy you calculate on the data set you do not use for training, but you use (during the training process) for validating (or “testing”) the generalisation ability of your model or for “early stopping”.

Can validation loss be more than 1?

Typically the validation loss is greater than training one, but only because you minimize the loss function on training data. I recommend to use something like the early-stopping method to prevent the overfitting. The results of the network during training are always better than during verification.

How do I fix overfitting and Underfitting?

Using a more complex model, for instance by switching from a linear to a non-linear model or by adding hidden layers to your neural network, will very often help solve underfitting. The algorithms you use include by default regularization parameters meant to prevent overfitting.

### What’s the difference between validation loss and training loss?

If validation loss << training loss you can call it underfitting. Your aim is to make the validation loss as low as possible. Some overfitting is nearly always a good thing. All that matters in the end is: is the validation loss as low as you can get it. This often occurs when the training loss is quite a bit lower.

What to do about validation loss in deep learning?

If validation loss > training loss you can call it some overfitting. If validation loss < training loss you can call it some underfitting. If validation loss << training loss you can call it underfitting. Your aim is to make the validation loss as low as possible. Some overfitting is nearly always a good thing.

How are learning curves calculated for train validation?

In this case, two plots are created, one for the learning curves of each metric, and each plot can show two learning curves, one for each of the train and validation datasets. Optimization Learning Curves: Learning curves calculated on the metric by which the parameters of the model are being optimized, e.g. loss.

## How is training loss related to overfitting?

The training loss remains flat regardless of training. The training loss continues to decrease until the end of training. Overfitting refers to a model that has learned the training dataset too well, including the statistical noise or random fluctuations in the training dataset.