### Logistic Regression 1 – Classification, Logistic Regression and Sigmoid Function

In previous series of posts we discussed [simple and multivariate linear regression]() that can be used to predict target features with continuous values. Besides that, there are other prediction problems with categorical target features and we want to train a model so that we can use it to predict the class of unknown data. Logistic regression is one of these models.
Classification Problem Imagine we have a tumor dataset which contains the Size of tumor and whether the tumor is Malignant or not.