MullOverThing

Useful tips for everyday

# What is the loss function used in logistic regression?

## What is the loss function used in logistic regression?

Log Loss is the loss function for logistic regression. Logistic regression is widely used by many practitioners.

What is the loss function in a neural network?

The Loss Function is one of the important components of Neural Networks. Loss is nothing but a prediction error of Neural Net. And the method to calculate the loss is called Loss Function. In simple words, the Loss is used to calculate the gradients. And gradients are used to update the weights of the Neural Net.

### How do you reduce loss in Ann?

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. Increase the size of your model (either number of layers or the raw number of neurons per layer)

Why do we need to define loss function in learning based algorithms such as logistic regression?

At its core, a loss function is a measure of how good your prediction model does in terms of being able to predict the expected outcome(or value). We convert the learning problem into an optimization problem, define a loss function and then optimize the algorithm to minimize the loss function.

#### What is the logistic regression cost function?

Non-convex function. For logistic regression, the Cost function is defined as: −log(hθ(x)) if y = 1. −log(1−hθ(x)) if y = 0.

What is the difference between the cost function and the loss function for logistic regression?

The terms cost and loss functions almost refer to the same meaning. The cost function is calculated as an average of loss functions. The loss function is a value which is calculated at every instance. So, for a single training cycle loss is calculated numerous times, but the cost function is only calculated once.

## What is the difference between loss function and cost function?

Yes , cost function and loss function are synonymous and used interchangeably but they are “different”. A loss function/error function is for a single training example/input. A cost function, on the other hand, is the average loss over the entire training dataset.

Which is the best loss function?

Mean Squared Error Loss The Mean Squared Error, or MSE, loss is the default loss to use for regression problems. Mathematically, it is the preferred loss function under the inference framework of maximum likelihood if the distribution of the target variable is Gaussian.

### How do you minimize losses?

An optimization problem seeks to minimize a loss function. An objective function is either a loss function or its negative (in specific domains, variously called a reward function, a profit function, a utility function, a fitness function, etc.), in which case it is to be maximized.

What are the purposes of loss function?

Loss functions measure how far an estimated value is from its true value. A loss function maps decisions to their associated costs. Loss functions are not fixed, they change depending on the task in hand and the goal to be met.

#### Can a loss function be used in logistic regression?

Linear regression uses Least Squared Error as loss function that gives a convex graph and then we can complete the optimization by finding its vertex as global minimum. However, it’s not an option for logistic regression anymore.

What is the cost of a loss function?

If y = 1, looking at the plot below on left, when prediction = 1, the cost = 0, when prediction = 0, the learning algorithm is punished by a very large cost. Similarly, if y = 0, the plot on right shows, predicting 0 has no punishment but predicting 1 has a large value of cost.

## How are loss functions used in supervised learning?

This series aims to explain loss functions of a few widely-used supervised learning models, and some options of optimization algorithms. In part I, I walked through the optimization process of Linear Regression in details by using Gradient Descent and using Least Squared Error as loss function. In this part, I will move to Logistic Regression.

When to use loss function in optimization process?

In calculating the error of the model during the optimization process, a loss function must be chosen. This can be a challenging problem as the function must capture the properties of the problem and be motivated by concerns that are important to the project and stakeholders.