Table of Contents

- 1 What is the difference between the cost function and the loss function for logistic regression?
- 2 Which algorithm is used in logistic regression?
- 3 Why logistic regression is called regression?
- 4 Why logistic regression loss function is convex?
- 5 Why linear regression cost function can not be used for logistic regression?
- 6 What is W in linear regression?
- 7 What is the accuracy of logistic regression?
- 8 How do you find the odds of success in logistic regression?

## 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. But, loss function mainly applies for a single training set as compared to the cost function which deals with a penalty for a number of training sets or the complete batch. The loss function is a value which is calculated at every instance.

## Which algorithm is used in logistic regression?

Note: Logistic regression uses the concept of predictive modeling as regression; therefore, it is called logistic regression, but is used to classify samples; Therefore, it falls under the classification algorithm.

**Why can’t we use mean square error MSE as a cost function for logistic regression?**

Mean Squared Error, commonly used for linear regression models, isn’t convex for logistic regression. This is because the logistic function isn’t always convex. The logarithm of the likelihood function is however always convex.

**What is the equation of logistic regression?**

log(p/1-p) is the link function. Logarithmic transformation on the outcome variable allows us to model a non-linear association in a linear way. This is the equation used in Logistic Regression. Here (p/1-p) is the odd ratio.

### Why logistic regression is called regression?

Logistic Regression is one of the basic and popular algorithms to solve a classification problem. It is named ‘Logistic Regression’ because its underlying technique is quite the same as Linear Regression. The term “Logistic” is taken from the Logit function that is used in this method of classification.

### Why logistic regression loss function is convex?

To prove for any log(x), 2nd derivative of log(x) is -1/x^2 which is concave. For f function being concave, -f is convex [basic theorem of convexity]. That means, – log(x) is convex, so is – log(1 – x). That is why we use this as our cost function during logistic regression.

**Why we are using logistic regression?**

It is used in statistical software to understand the relationship between the dependent variable and one or more independent variables by estimating probabilities using a logistic regression equation. This type of analysis can help you predict the likelihood of an event happening or a choice being made.

**Why is logistic regression supervised?**

Logistic regression is a supervised learning classification algorithm used to predict the probability of a target variable. The nature of target or dependent variable is dichotomous, which means there would be only two possible classes.

#### Why linear regression cost function can not be used for logistic regression?

The hypothesis of logistic regression tends it to limit the cost function between 0 and 1. Therefore linear functions fail to represent it as it can have a value greater than 1 or less than 0 which is not possible as per the hypothesis of logistic regression.

#### What is W in linear regression?

Simple linear regression uses traditional slope-intercept form, where m and b are the variables our algorithm will try to “learn” to produce the most accurate predictions. A more complex, multi-variable linear equation might look like this, where w represents the coefficients, or weights, our model will try to learn.

**Why logistic regression is called logistic regression?**

**How do you calculate the logit(P) in logistic regression?**

Logistic regression forms this model by creating a new dependent variable, the logit(P). If P is the probability of a 1 at for given value of X, the odds of a 1 vs. a 0 at any value for X are P/(1-P). The logit(P) is the natural log of this odds ratio. Definition : Logit(P) = ln[P/(1-P)] = ln(odds).

## What is the accuracy of logistic regression?

Logistic Regression model accuracy(in \%): 95.6884561892 At last, here are some points about Logistic regression to ponder upon: Does NOT assume a linear relationship between the dependent variable and the independent variables, but it does assume linear relationship between the logit of the explanatory variables and the response .

## How do you find the odds of success in logistic regression?

For binary logistic regression, the odds of success are: π 1 − π = exp(Xβ). By plugging this into the formula for θ above and setting X ( 1) equal to X ( 2) except in one position (i.e., only one predictor differs by one unit), we can determine the relationship between that predictor and the response.

**What is the formula for multiple binary logistic regression?**

The multiple binary logistic regression model is the following: π(X)= exp(β0 +β1X1 +…+βkXk) 1+exp(β0+β1X1+…+βkXk) = exp(Xβ) 1+exp(Xβ) = 1 1+exp(−Xβ), π (X) = exp (β 0 + β 1 X 1 + … + β k X k) 1 + exp (β 0 + β 1 X 1 + … + β k X k) = exp