logistic regression.

logistic regression.

logistic regression with a

Let's start talking about logistic regression.

light of logistic regression, the Support

logistic regression and we're seeing what the mathematical formula is defining the hypothesis for logistic regression.

For such situations there is a model called logistic regression, which uses a slightly more complicated model than linear regression, which goes as follows .

So, for logistic regression, we had two terms to our objective function.

We already have linear regression and we have logistic regression, so why do we need, you know, neural networks?

Now let's think about what we will like the logistic regression to do.

Could we use Naive Bayes, k Nearest Neighbors, Support Vector Machines, Logistic Regression.

We're going to model a neuron as just a logistic unit.

logistic regression, I'm going to modify this a little bit, and make the hypothesis

Logistic Regression is actually a classification algorithm that we apply to settings where the

How about if we were doing a classification problem and say using logistic regression instead.

A plus B. So for logistic regression if we send a very large value of

So, simple logistic regression together with adding in maybe the quadratic or the cubic features

In the next video we'll start working out the details of the logistic regression algorithm.

That's the term that a single training example contributes to the overall objective function for logistic regression.

If you want to apply logistic regression to this problem, one thing you could do is apply

So, here's a simple regression equation, or, a simple path model.

And that's called the support vector machine, and compared to both the logistic regression and neural networks, the

line similar to logistic regression but this is going to be the straight line in this posh inning.

Where instead of having basically just one logistic regression output unit, we may instead have K of them.

And finally, the second term here is the regularization term similar to what we had for logistic regression.

So you'll see that the regression model is really just the equation.

So, that whole regression equation is represented in this simple path model.

Let F of XP, or linear function, and the output of logistic regression is obtained by the following function

This model is called linear regression or this, for example, is actually linear regression with one variable, with the variable being x.

Up to this point, I've been saying that one regression equation is one model.

We'll develop an algorithm called logistic regression, which is one of the most popular and most widely used learning algorithms today.

And the term logistic function, that's what give rise to the name logistic progression.

So, in logistic regression we have our familiar form of the hypotheses there and the sigmoid activation function shown on the right.

like we had for logistic progression.

Clearly a linear regression model is a very poor one to explain this data over here.

Just two simple regressions and model three is the multiple regression with both predictors in there.

That's the way to interpret the regression coefficients when there are multiple predictors in the model.

linear regression.

The cost function we use for the neural network is going to be a generalization of the one that we use for logistic regression.

Now, this didn't really come up much in simple regression because the model was just one predictor.

And this data set happens to be fittable by a linear regression model without any residual error.

The regression equation is just the model. You'll see that our, our models will get more complex.

So, it's a pretty close approximation to the cost function used by logistic regression except that it is now made out of two line segments.

The second bit of notational change, we're just designating the most standard convention, when using as the SVM, instead of logistic regression as a following.

The other thing I eluded to last lecture, and we didn't really get into simple regression is this idea when model R and model R squared.