As you can see from the graph, a(sigmoid(x)) varies between 0 and 1. This makes sigmoid function and in turn logistic regression suitable for binomial classification problem. That means we can use logistic regression or sigmoid function when the target varible has only two values(0 or 1). This makes it suitable for our purpose, in which we are trying to predict the gender of the celebrity from images. Gender(our target variable) has only two values in our dataset, male(0) and female(1).

In this series, I will talk about training a simple neural network on image data. To give a brief overview, neural networks is a kind of supervised learning. By this I mean, the model needs to train on historical data to understand the relationship between input variables and target variables. Once trained, the model can be used to predict target variable on new input data. In the previous posts, we have written about linear, lasso and ridge regression.